Wayne Rooney could miss Manchester United's final home game of the season as he is still struggling to overcome a groin injury.
Rooney sat out the 1-0 defeat to Sunderland last weekend due to a combination of the injury and a stomach bug.
Interim player-manager Ryan Giggs revealed on the eve of United's home game against Hull that the 28-year-old has still not fully recovered from the injury.
"Wayne is probably struggling for the game. He's not quite recovered. We'll continue to monitor him," Giggs told MUTV.
Sources close to Rooney insisted last week that the groin complaint would not affect the striker's chances of being fit for the World Cup.
But just a week ahead of his squad announcement, England manager Roy Hodgson will be anxious, no doubt, that his star striker is carrying a knock.
Rooney's potential absence for the Hull game could see Giggs hand Robin van Persie his first start in seven weeks, as the Dutch striker has now fully recovered from a knee injury.
Tuesday will be the final home match of Giggs' temporary reign, with Holland coach Louis van Gaal expected to be appointed as David Moyes' successor in the coming days.
Van Gaal has been urged to include Giggs and his coaches Phil Neville, Nicky Butt and Paul Scholes among his staff by former United skipper Bryan Robson.
"I think it would be very disappointing for those lads not to be kept on, in whatever role, as they are part of Manchester United," Robson said.
"The fans would be very disappointed if they don't have a future in the club.
"I have read that Van Gaal wants to bring in a goalkeeper coach, a fitness coach, and (Patrick) Kluivert as his assistant.
"If you are talking about bringing all these people in you have to make sure that you are making the right decision and you are not allowing them too much rope.
"It is up to the board to step in and say, 'You can have leeway with this, but there are definitely restrictions on this part of the club'.
"That has to come from the club rather than the new coach. Sometimes I think when you go into a new club, why not give the staff a chance?"
United have always maintained the fact that Van Gaal will not be able to take over fully until after the World Cup is not a problem.
Holland's World Cup preparations begin on Wednesday when the Eredivisie-based players in Van Gaal's squad meet for their first training camp in Hoenderloo, which is 50 miles to the south-east of Amsterdam.
The cameras will focus on the Holland manager, but he has chosen not to hold his press conference until May 13, when he will announce his provisional 30-man squad for the finals in Brazil.
The fact that the squad does not meet up until Wednesday afternoon leaves open the possibility of Van Gaal attending United's game versus Hull, which will be significant for a number of reasons.
Nemanja Vidic will play his final game at Old Trafford while it could be the last home game for Rio Ferdinand and Patrice Evra, both of whom are out of contract in the summer.
And it may well be the last time United fans get a glimpse of Giggs for a while as he has not been assured that he will figure in Van Gaal's plans - either as a player or coach.
The interim boss did not rule out naming himself in the matchday squad when quizzed on the matter at the weekend.
Giggs said: "Of course, the perfect scenario is me coming on and scoring a goal, the winning goal, and hopefully everyone will be happy but it doesn't always work like that. We'll have to wait and see what happens on the night."