Phil Jones may have played just two games for United but he's already shown his value to the squad, according to his manager.
Jones featured in the centre of defence in the win over Chicago at the weekend, before being switched to right-back for the victory over the MLS All-Stars on Wednesday.
Sir Alex was impressed by both displays and feels Jones' versatility - he can also play in midfield - will be an important asset to the squad.
"At 19 years of age he's very versatile," the boss told reporters after the 4-0 win over the All-Stars. "He's mobile, he's determined and last season he played quite a few games for Blackburn in the centre of midfield.
"We thought we'd try him at right-back. It's something we can keep as an option for us. [Chris] Smalling has also played there two or three times now. With the experience our centre backs have, its a very good option for us."
The win in New Jersey over Beckham and co. kept up United's 100 per cent record on tour and while Sir Alex was pleased with the result, he was more satisfied with the way his players are coming along from a fitness perspective.
"The fitness is improving all the time, the games help with that, of course," he added. "We've had some good training sessions as well and we've tried to get tempo into our game and some rhythm.
"It's also important all the players are given as much game time as possible. Tonight was the first time we gave the starters a good hour's work. Saturday [against Barcelona in Washington DC] will be similar - the first XI that play will get an hour before we change it."