The Red Devils signed the Serbia international in a £40m deal from defending Premier League champions Chelsea earlier this month.
Matic won the Premier League twice and the EFL Cup during his three-and-a-half season stay at Stamford Bridge.
The 29-year-old was an important member of Antonio Conte’s title-winning team as the Blues finished seven points clear of their closest title rivals Tottenham Hotspur.
The holding midfielder has wasted no time having a big impact on Manchester United after Matic produced a dominant performance in a 4-0 victory over West Ham at Old Trafford on Sunday afternoon.
Former Spurs forward Crooks has expressed his confusion about Chelsea’s decision to sell Matic to Manchester United and strengthen their direct title rival.
“I watched Matic on numerous occasions during his time at Stamford Bridge, and while he didn’t have a blistering season, he played a fundamental role in Chelsea winning the title,” Crooks told BBC Sport.
“No sooner had the hangover from the title celebrations subsided, than Matic was off to United producing what can only be described as a majestic debut performance.
“West Ham were blown away as Matic provided Paul Pogba with the freedom to roam, Henrikh Mkhitaryan with the freedom to probe and Juan Mata to do just whatever he liked.
“Landing Matic has been an extraordinary piece of business by Manchester United and that is why I have tipped them for the title.”
Matic was part of Jose Mourinho’s Chelsea team that won the Premier League title and the League Cup in the 2014-15 season.
The Serbia midfielder scored seven times in 151 games during his spell at Stamford Bridge.
Manchester United have also signed Everton striker Romelu Lukaku and Benfica defender Victor Lindelof.
The Red Devils lost 2-1 to La Liga giants Real Madrid in the Uefa Super Cup last week.
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