Manchester United anxiously anticipate the results of Wayne Rooney's ankle scan, following his injury in Tuesday's 2-1 Champions League quarter-final defeat at Bayern Munich. United were dealt a double blow when Ivica Olic scored in injury time to win the first leg for the hosts, only for Rooney to leave the pitch injured afterwards. "He's obviously hurt his ankle, we'll know better on Wednesday. It's too early to say. I don't think it's terribly serious, but we'll wait and see," manager Ferguson said. The England hitman, who left Allianz Arena on crutches, is almost certain to miss Saturday decisive Premier League clash with Chelsea. According to reports, Rooney is facing up to four weeks on the sidelines.