Cristiano Ronaldo doubtful for Borussia Dortmund clash

Cristiano Ronaldo is an injury doubt for Real Madrid's Champions League semi-final second leg against Borussia Dortmund on Tuesday.

The Portuguese forward, 28, sat out with a thigh injury as Real recorded a 2-1 win over city rivals Atletico Madrid in La Liga on Saturday.

He then missed training with the rest of the squad on Sunday and instead worked alone with Madrid's fitness team.

Ronaldo is the top scorer in this season's Champions League with 12 goals in 11 matches.