RIO DE JANEIRO, Feb. 15 (Xinhua) -- Spanish tennis star Rafael Nadal is facing a "must win" tournament according to Sky Sports' Barry Cowan, as the Rio Open gets underway on Monday.

Nadal, currently fifth in the world, lost in the semi-finals of the Argentina Open this weekend against Dominic Thiem, going down 6-4, 4-6, 7-6, 7-4, who went on to lift the title.

Thiem will also be in action in Rio this week, as will clay court specialists David Ferrer and Fabio Fognini.

The tournament will be Nadal's fifth appearance in Brazil, where he holds a 17-1 record. He has won titles in Costa do Sauipe in 2005, Sao Paulo in 2013 and Rio de Janeiro in 2014.

Nadal's only defeat on Brazilian soil came last year, against Fognini. This year, the former world No. 1 starts his campaign against compatriot Pablo Carreno Busta.