Rooney has started no more than seven successive games in a stop-start season, with manager Alex Ferguson acknowledging on several occasions that the 27-year-old's physical make-up requires three games after each comeback before he is fully match-fit.
He appeared to be in some discomfort in Qatar, rolling up his shorts and shaking his head at one stage during short sprints in the training session.
United's Ashley Young could also be out for longer than Ferguson had anticipated when he said last week that the England international might be absent for only a week or two.
Young left Old Trafford on crutches after the 2-1 win over Liverpool earlier this month, following a first-half collision with Daniel Agger that caused damage to his knee – worryingly, on the same right leg that has caused him so much trouble over the last year or so.
The initial prognosis led to Ferguson's optimism when he discussed the player last week, though Young may not be back until next month at the earliest.
Rooney's only start this year was the FA Cup third-round replay against West Ham, in which his goal and missed penalty summed up the frustrations of a season in which he has scored 12 times in all competitions. In his regular absences, Robin van Persie has very much become the main man up front for United with 24 goals in 31 appearances this season.
Rooney will certainly be looking to improve his strike rate as United seek to progress in three competitions, with Fulham visiting Old Trafford in the FA Cup fourth round on Saturday.
The two-legged Champions League last-16 clash with Real Madrid also looms large on the horizon and Ferguson will be keen to get Rooney back to full fitness and match sharpness before the first leg of that tie on February 13.
The England striker missed his team's 4-3 St Stephen's Day win over Newcastle after he tore a ligament in the back of his knee at training on Christmas Day, before sitting out United's next two fixtures over the festive period against West Brom and Wigan. (© Independent News Service)