Philadelphia Union missed the chance to kick off the MLS season with a win after 10-man Colorado Rapids battled to a 0-0 draw at PPL Park.

The hosts started much the better of the sides as Maurice Edu blazed over from a corner, while Andrew Wenger's curling effort cannoned off the crossbar.

Jim Curtin's side grew more dangerous as the half went on and Fernando Aristeguieta, on his Union debut, failed to convert a near-post opportunity on the half-hour mark.

Philadelphia would have earned a half-time lead if not for Clint Irwin, who produced an important save with his feet to keep out Sebastien Le Toux on 44 minutes.

Aristeguieta spurned another good chance after the break, while Senegalese striker Dominique Badji went close for Rapids in a rare chance for the visitors.

The hosts were gifted an easier route to victory when Bobby Burling picked up a second yellow card after 68 minutes.

However, Curtin's side failed to make the most of their numerical advantage as Colordo held on for a hard-fought point.