[7] After beginning the following season again in the starting XI (nine matches, one goal), Sereno eventually terminated his contract and, on 1 February 2010, signed with Real Valladolid in Spain for five months.

[8] He made his debut for his new team on 20 March 2010, playing the entire 2–0 away victory over Deportivo de La Coruña.

[9] In late June 2010, after Valladolid's relegation in La Liga, Sereno returned to his country, signing with FC Porto on a free transfer.

[11] Sereno made his Bundesliga debut on 27 August 2011, playing the full 90 minutes of a 4–3 away defeat of Hamburger SV.

He made his Süper Lig debut on 15 September, featuring the full 90 minutes in a 1–1 draw at Gençlerbirliği SK.

[23] On 15 September he returned to the Indian top tier, joining Chennaiyin FC for free[24] and going on to act as captain for the eventual champions.

[27] Sereno made his debut for Portugal on 10 June 2013, playing the second half of a 1–0 friendly win against Croatia in Geneva.