England striker Rooney was already an Old Trafford legend after over four years at the club, but the emergence of Welbeck as a forward partner for both club and country offered a tantalising opportunity of success at all levels.
The club partnership of Rooney, 27, and Welbeck, 22, may have been diluted significantly by the arrival of Robin van Persie, but the English strike pairing has to be favoured for the World Cup in 2014.
Welbeck made his international bow in the 1-1 friendly draw with Ghana at Wembley in March 2011 and has since made his own mark for the Three Lions with five goals in 14 appearances.
At international level, the pairing of Welbeck and Rooney has become a favourite for England manager Roy Hodgson.
In Rooney’s darkest hour, the 2010 World Cup in South Africa, the striker cut a forlorn figure up front and was shorn of the support he received on a regular basis at Old Trafford.
But the emergence of Welbeck last season for both club and country clearly lifted Rooney, and his return of 38 goals from 49 games for United and England was testament to a rejuvenated forward.
Welbeck holds the ball up well, an area where England have been lacking, allowing Rooney more freedom to find a run rather than merely chasing to set up his own chances.
The capture of Van Persie at Old Trafford from Arsenal this summer has confined Welbeck so far this season, which will be a concern for Hodgson and England.
But dislodging Dimitar Berbatov and Javier Hernandez from the United starting lineup last season was no mean feat, and Welbeck thrived on the challenge.
Ostensibly, Welbeck’s game is dominated by pace, movement and possession. But his passing also provided a new dimension for Rooney, while his own accuracy and work rate cannot be underestimated.
Welbeck’s goal-scoring ratio does need improvement and the form of Van Persie may make that difficult to work on consistently at club level.
But witness also some of his goals for England, notably the sublime backheel which defeated Sweden at the European Championships this year and you know Welbeck, who has scored five times in his 14 international appearances, has the ability.
Can England afford to gamble on not having Welbeck in Rio?