Diogo Filipe Guerreiro Viana (born 22 February 1990) is a Portuguese professional footballer who plays as a right winger for Trofense.

Formed at Sporting CP and Porto, he played 129 Primeira Liga games for Gil Vicente, Belenenses, B-SAD and Braga, while also having spells abroad in the Netherlands, Bulgaria and Romania.

In June 2008 the 18-year-old was transferred to FC Porto as part of a deal involving Hélder Postiga,[2] with the northerners receiving €2.5 million whereas the Lisbon club retained 50% of his rights.

[3] In the 2008–09 season, whilst still a junior, he made his debut with the first team, playing four Taça da Liga matches and totalling 55 minutes in two wins and two losses.

[6] Viana signed with First Professional Football League (Bulgaria) club PFC Litex Lovech in June 2015,[7] after two years in the Primeira Liga with Gil Vicente FC.

[13] On 25 June, he moved abroad again, with compatriot João Miguel to FC Argeș Pitești in the Romanian Liga I.