Mário Sérgio joined Sporting CP on 25 June 2003 on a four-year contract, being the first signing of manager Fernando Santos; he said upon his arrival: "I am an ambitious player. I have fought for this opportunity and now want to show my worth".[4] However, three years later and with only 18 competitive appearances to his credit, also being loaned to fellow league side Vitória de Guimarães,[5] he was released.[6]
Immediately after leaving the Lions, Mário Sérgio signed for two years with Associação Naval 1º de Maio also in the top division.[7] He was an undisputed starter during his tenure, scoring his third and last league goal on 14 January 2007 to contribute to a 3–0 away victory over Vitória de Setúbal.[8]
Mário Sérgio renewed his link for two more years on 25 September 2009, keeping him at the club until 2012.[11] In March 2012, he became the first player to appear in 100 league games for Metalurh, achieving this feat against SC Tavriya Simferopol; he was released midway through that month alongside two other players, however,[12] having scored twice in the competition, both goals coming against Karpaty in September 2011.[13]
Mário Sérgio agreed to a two-year extension on 6 December 2014, running until June 2017.[21]
Later years
On 30 December 2016, after he cut ties with APOEL, free agent Mário Sérgio signed a six-month deal with Apollon Limassol with an option for a further season.[22] He subsequently returned to his homeland, where he played for Varzim S.C.[23] and F.C. Felgueiras 1932.[24]
^"Mário Sérgio já assinou" [Mário Sérgio has already signed]. Record (in Portuguese). 6 June 2006. Archived from the original on 13 April 2015. Retrieved 7 April 2015.
^Металлург 1:0 Карпаты [Metalurh 1:0 Кarpaty] (in Ukrainian). Championat. 19 August 2008. Retrieved 24 February 2015.
^"Mário Sérgio renova com Metalurg" [Mário Sérgio renews with Metalurg]. Record (in Portuguese). 25 September 2009. Archived from the original on 27 February 2015. Retrieved 27 February 2015.
^Gonçalves dos Santos, Pedro (18 May 2004). "Sub-21: Euro ambição" [Under-21: Euro ambition]. Record (in Portuguese). Archived from the original on 13 April 2015. Retrieved 7 April 2015.