Park jetted off to captain South Korea in the 2011 AFC Asian Cup and missed seven games for United after the turn of the year. Upon his return from the subsequent tournament, he was ruled out for one month due to an hamstring injury which occurred during training. He returned to action for the first time since Boxing Day on 2 April, playing 64 minutes of a 4–2 away win over West Ham United. On 12 April 2011, Park scored his first goal since the turn of the year when he scored the winning goal in the Champions League quarter-final second leg tie against Chelsea, ending in a 2–1 win. On 8 May, Park assisted Javier Hernández's opening goal with an accurate through-ball just 36 seconds after the start of the crucial match, which virtually decided United's league title with a 2–1 victory over rivals Chelsea. On 22 May, he scored a goal and set up the second goal for Anderson in the last match of the season against Blackpool. Park played in another Champions League final, against Barcelona in 2011, which United lost 3–1.