Neville has flown back to England for treatment and has been ruled out of the remainder of United's Far East tour, the Audi Cup in Munich next week, when United will place two games, the first against Boca Juniors on Wednesday and, in all probability, the Old Trafford friendly with Valencia on August 5.
"Gary Neville tweaked his groin yesterday in training," said Sir Alex Ferguson following his side's 3-2 win over FC Seoul.
"He will probably be ready in about 10 days.
"It would have been silly to keep him here if he was not going to play so we sent him home this morning."
Given the muscular injuries that sidelined Neville for the best part of two seasons, it is a worrying development for the 34-year-old, although there is no suggestion at this stage that his career is under threat.
At least Ferguson has plenty of options at right-back, with Rafael Da Silva, Wes Brown and John O'Shea all capable of fulfilling the role.
It is up front where Ferguson is deriving most pleasure from the pre-season campaign though.
Wayne Rooney and Federico Macheda were both on target for the second time in pre-season, with Dimitar Berbatov breaking his duck by nodding home the winner midway through the second half.
For Macheda in particular, an impressive Far East tour is a major bonus, as it will give his manager faith that, in the 17-year-old, he has someone capable of being fourth striker to Rooney, Berbatov and Michael Owen.
"Federico's goal was excellent," enthused Ferguson.
"His movement was very good and he always seems to do well when he gets on the shoulder of defenders.
"It is really pleasing to see your strikers scoring.
"Obviously the main ones are going to be Owen, Rooney and Berbatov and I am very comfortable with that.
"But if Federico continues to progress, it will be a big advantage to us because it would give us an extra player from the word go."
The other star of the show was Park Ji-sung, who was sent on for the final 17 minutes despite being well short of match practice after an extended summer break.
Park received huge cheers every time his face was shown on the big screens at either end of the stadium and the ovation he was given when he came on was similar to those David Beckham tends to receive.
His reward for four years' hard graft will be a new United contract, which Ferguson feels is fully deserved.
"His performance level in the last few years has been outstanding," said Ferguson.
"His contract is coming to an end so giving him a new one is an appropriate step to ensure he stays with us for the next few years.
"He is a really top player and we want him to remain at Old Trafford.
"He is nowhere near the level of fitness we require just yet but in view of the fact this match was in his home country, I thought it was the right thing to do to give him some of the match."