Robben was inflicted with yet another injury in a match against Liverpool on 20 January 2007. Robben made his return in a 3–0 victory against Middlesbrough in February, driving in a shot that took a deflection past Mark Schwarzer for an own goal by Abel Xavier. He came on as a substitute for Claude Makélélé in the 2007 League Cup final against Arsenal and set up the winning goal for Didier Drogba. Robben scored a goal in the second round of the Champions League against Porto, which led to Chelsea winning the tie 3–2 on aggregate. At the end of March 2007, Robben underwent a knee operation after sustaining a knee injury upon returning from international duty that was expected to rule him out for at least four weeks. He only made two further appearances for Chelsea, both of which were as a substitute and both of which would prove to be key games for the club. His first appearance since returning from injury was against Liverpool in the Champions League semi-final second leg which went to penalties. Robben went on to have his penalty saved by Pepe Reina, and Chelsea ultimately lost.