A hard-working box-to-box player who was captain of the Brazilian u-20 team. In October 2005 Lucas made his debut for Gremio in the Brazilian second division. Gremio were promoted and in Lucas' first season in the top-flight in 2006 when Gremio finished third he became the youngest-ever player to receive Placar magazine's Bola de Ouro (Golden Ball), given to the best player in the Brazilian league, an honour previously won by the likes of Zico, Falcao, Careca, Romario, Kaka and Carlos Tevez. Just before joining Liverpool, Lucas went all the way to the two-legged final in Copa Libertadores where Boca Juniors outplayed the Brazilian team, winning 5-0 on aggregate. BBC's expert on South American football, Tim Vickery, was optimistic about Lucas' chances of making a name for himself at Liverpool. "These moves are always a gamble, but I think this is a good one. He's an exciting player of a type that Brazilian football hasn't produced too many of recently. Of late their central midfielders have tended to be 'holders' who sit and allow the full-backs to push forward. Lucas is different. He's a big, blonde figure whose power and physical strength comes with attacking ability. He can pass well and loves to rumble forward. He gets on the scoresheet both with blistering shots from range and from bursting beyond the strikers."
Lucas took part in 32 competitive matches during his first season in English football. His highlight of the season came when he thundered an equalising goal into the top corner after non-League Havant & Waterlooville had taken a shock early lead in the FA Cup at Anfield in January 2008. Lucas was 'capped' by his country for the first time in August 2007 and played for Brazil's Olympic team in Beijing 2008 that finished third. He was one of two Brazil players who were sent off in the semi-final defeat to Argentina. Alonso and Mascherano continued to be the preferred choice in midfield by Rafa in the 2008/09 season and Lucas only twice made the starting line-up. Lucas showed his inexperience when he was sent off after 75 minutes for a second booking when he brought down Joleon Lescott against Everton at Goodison Park in a FA Cup fourth round replay. Following Alonso's move to Real Lucas featured more than ever before and only Reina (52), Carragher and Kuyt (53) played in more first-team matches than the previously much-maligned Lucas, in 2009/10. Scapegoat for many a poor team performance in the past, the young Brazilian, who turned 23 during the season, won over huge sections of the fanbase with assured displays that made him probably the most improved player of any of the first-team squad during the season. He was picked from the start for the first six matches of the season, something he had never achieved before, and continued to be a regular throughout the campaign. Lucas hardly put a foot wrong and was the fourth most prolific tackler in the Premier League.
At the end of March 2011 the Brazilian signed a new long-term deal that tied him to LFC until 2015. His future at the club didn't look bright a couple of years back, even shamefully booed by his own fans. He admitted he needed some time to settle in: “Things were not looking good and some supporters were obviously not happy. The move to Liverpool represented a change of country, language and there was also the not so small detail that I was only 20 and arriving at a traditional club in one of the most demanding leagues in the world. Also, few people seemed to remember Liverpool had a group of players that had made two of the last three Champions League finals. Maybe the supporters thought a Brazilian midfielder would do magic. In Gremio I had carte blanche to go forward and participate more in the attacking plays. But things had to change when I arrived in Liverpool, where I am used much more as a holding midfielder. That transition took time and made settling in even more challenging."
Javier Mascherano left early in the 2010/11 season and fans wondered if Lucas was ready to take over his mantle. Few could argue Lucas has developed into an equally strong player as the Argentinian and crucially more composed on the field. Lucas was voted Standard Chartered's Player of the Season in 2010/11 as he became one of Liverpool's key players, having made steady progress in the sometimes unforgiving Anfield spotlight. Not renowned as a goalscorer, he got Liverpool's campaign in the group stage of the Europa League off to a thrilling start. Coming on as a substitute he took only two minutes to make his mark on an autumnal evening at Anfield by driving a long-range shot past the Steaua Bucharest goalkeeper to reclaim the lead for his team and help to ensure three vital points. Lucas' 2011/12 season came to a shuddering halt when he was stretchered off the Stamford Bridge pitch during Liverpool's League Cup quarter-final with Chelsea at the end of November having damaged the anterior cruciate ligament in his left knee. His absence was more keenly felt than anyone's else's and Liverpool's midfield fell apart without him in the second half of the campaign when the club lost 11 out of 19 League games! Lucas returned in August, but suffered another setback when he injured his thigh in the warm-up when champions Manchester City visited Anfield on 26 August 2012. Lucas said he would shake the injury off, but he only lasted five minutes before being replaced by Jonjo Shelvey. He was sidelined until 1 December and has been slowly getting his match fitness to normal levels following such a lengthy absence.
The injury received in only the second Premier League match of 2012/13 kept Lucas out of the first-team picture for over three months. Once he got back into the team, however, he kept his place until the end of the season and made his 200th appearance for the club in the home fixture against West Bromwich Albion in February. Two months later the midfielder signed a new contract which the club described as 'long-term'. Appearing in twenty-nine of the club's forty-three competitivematches (67%) in 2013/14 was a good statistic for a man who was struggling to get to his best form. He was used as a substitute twice as many times as he had been in Brendan Rodgers' first season but he always gave maximum effort even if at times it looked as if he hadn't quite left his injury concerns behind him. Lucas failed to make the 23-man squad picked by Luiz Felipe Scolari to represent the hosts at the 2014 World Cup finals. Just before the main squad was announced. Lucas Leiva's services to the Liverpool FC Foundation were rewarded at the club's Players' Awards Dinner with the Bill Shankly Award as someone who has upheld the club's values, showing dignity, unity, commitment and ambition.
Lucas passed his 28th birthday during the 2014-15 season, in which he only played in just over half of Liverpool's Premier League matches. He also appeared in twelve cup-ties and that took his total of appearances for the club up to 275. He was sometimes unavailable for selection because of injury, although had appeared to have made a good recovery from the serious anterior cruciate ligament injury he received at Chelsea towards the end of 2011. Steven Gerrard's departure meant he was now the longest serving player at the club in 2015-16 and although not part of Brendan Rodger's or Jurgen Klopp's preferred first eleven, he was always reliable and did his job when called upon. His total number of appearances, forty in all competitions, was his best total since 2010-11 but for the fifth season running he failed to find the net. Lucas's appearances were limited in 2016-17 but he did finally score a goal, in an FA Cup third round replay at Plymouth. Although he was put under no pressure to leave at the end of the season, Jurgen Klopp told him the club would not stand in his way if he wanted to look elsewhere and the popular Brazilian left Liverpool for Lazio in Serie A. Lucas was a key player for the Roman club, appearing in all but two of their Serie A games and scoring twice in 2017-18. He continued to be a firm favourite in 2018-19, helping Lazio to the Coppa Italia, winning the fans player of the year award and signing a contract extension keeping him at the club until 2022. In 2019/20 he was again a pivotal player, only missing out when he had knee problems or was suspended.
Over the next two seasons Lucas remained a regular in the Lazio side and continued to give his backing to Liverpool on social media. His contract expired in the summer of 2022 and although he had better offers from other unnamed clubs, he opted to return to Gremio, the side he had left fifteen years earlier who were now playing in Brazil's second tier. He told reporters at his unveiling "For me, it doesn't matter where Gremio is, what matters is having the opportunity to represent this team that means so much to me. The club made an effort to bring me and I made an effort to return, the most important thing is to put vanities and ego aside for a single objective, which is to return to Serie A." Lucas helped Gremio achieve that aim, scoring three times in seventeen appearances. However during pre season preparations a heart defect was discovered and on 17th March 2023 he announced his retirement from playing after receiving further medical advice.