In 2010, the last time he returned from an international tournament, his form for Manchester United was disastrous. More on that shortly.
In 2011, he begun the season fresher than ever, scoring five in his first three games, including a hat-trick in a 8-2 win over Arsenal. One of the reasons he was so effective was because he had a complete summer rest under his belt.
So with a Euro 2012 under his belt which gave him little to smile about and saw him, unfairly, take a lot of criticism, all eyes will be on how he will react when United kick-off away to his former club Everton next month.
He has rarely excelled on his visits to Goodison Park, but United will hope their star man can hit the ground running, with speculation currently running wild over whether he will be partnered by Robin Van Persie in attack.
Going back to 2010, the reasons for his woeful form were plentiful. He had a very unhappy and frustrating World Cup, his personal life was racked by self-inflicted tabloid scandal, and although we didn't realise at the time, he was having severe doubts over his future at the club.
That perfect storm is unlikely to trouble him again, and the question is not whether he will start the season poorly, but whether he can start it in the same scintillating form as last year?
He scored 27 league goals last year, a figure he will surely need to get close to again if United are to wrestle their title back from City, who for sure will not give it up easily.
After the Everton opener, United face Fulham at home, Southampton away, and Wigan at home. They are matches the club's talisman will fancy his chances of scoring in.
Replicating his early goalscoring run from last year could easily happen, Rooney is a player who needs a goal to start him off and tends to score in spurts. If he can bag one against Everton, then Fulham, Southampton and Wigan should be especially worried.
Much will depend on how quickly he can regain his fitness, he has not yet joined up with United's pre-season tour, and how he can fit in with any change of formation. Shinji Kagawa's arrival has speculated that United will change their tactics, and Rooney will be pushed further forward, but an arrival of a certain Dutchman could just complicate matters further.
Last season proved that every point, and every goal counts, and United can't afford Rooney to come in off the pace, as many criticised him for at Euro 2012.
The striker can blow hot or cold, and United need him to be red hot when they face the Goodison cauldron on August 20.
Can Rooney replicate his early season form from last year?
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