Arsenal manager Arsene Wenger believes Manchester United's recent burst of transfer activity is a result of their disappointment at finishing fourth in the Premier League last season.
Defender Matteo Darmian and midfielders Morgan Schneiderlin and Bastian Schweinsteiger have linked up with the United squad after completing their transfers, and Wenger expects their additions to give United a fresh edge next season.
"We knew they wouldn't be happy with finishing outside the top three and they would respond," he told reporters when asked about United's improved options.
"They have made some interesting signings. They came out of the season thinking they have to rebuild their midfield, and they did it by buying two important players -- Schweinsteiger and Schneiderlin.
"They are two top-class players -- one who is now coming up to the top level in Schneiderlin, and one who has done it all. It will be interesting to see how they mix with the other players."
Speaking in Singapore at the start of Arsenal's preseason tour, Wenger also reacted to confirmation that Manchester City have agreed a fee with Liverpool for Raheem Sterling, suggesting he had not got involved in bidding for the England man as he did not need a winger.
"It looked a done deal for a while because Sterling said he wanted to leave," he added. "For me, Sterling is a top-class player. It's a good buy for Man City. An expensive one, but they can afford it.
"Personally I like him. I didn't make a bid because he plays in an area where we have plenty of players. We have [Danny] Welbeck, [Theo] Walcott, [Alex Oxlade] Chamberlain, [Alexis] Sanchez, [Jack] Wilshere can play there, [Serge] Gnabry. He's a wide player basically, or behind the striker."
Wenger hinted that his summer transfer activity was not concluded following the high-profile capture of keeper Petr Cech from Chelsea.
"If we find ideally what we want, we are still hoping to do something else," he added. "It doesn't depend only on us, it depends on whether we can find them, but if we can find one or two players we will do it.
"We finished third last season and won the FA Cup. The pressure is on us to do better, but there are plenty of competitors to win the Premier League.
"You have seen the buys clubs have made already, but we will give absolutely everything to do it."