The two teams go head-to-head at the London Stadium on Sunday and Sinclair believes West Ham boast the stronger midfield.
Earlier this summer, Rice was a reported transfer target for Manchester United and Chelsea and he may have been playing for West Ham's opponents this weekend had the club's demands been met.
Unwilling to pay the reported £100million price tag, Rice stayed put to the delight of Hammers supporters and once again showcased his talents with a superb goal in the club's opening night win over Dinamo Zagreb in the Europa League.
His and his teammate Soucek's stellar performances were applauded by Sinclair, who reckons the pair could rival any midfield duo in the Premier League.
Sinclair told talkSPORT: "I've said it last season, we were talking about this exact fixture and I said Rice and Soucek would walk into the [Manchester] United team.
"I don't think the two or three holding midfielders [Fred, Scott McTominay and Nemanja Matic] would walk into the West Ham team.
"I think they're probably as good as you're going to get in the Premier League at the moment.
"Soucek brings his unique running power, he's a real boss in both boxes and Rice with his composure and his ability to run games at the back, it's absolutely brilliant."
The quality both players possess have helped David Moyes' team become strong competitors both in the Premier League and in Europe.
While many disagree with Rice's £100 million price tag, he is certainly invaluable to his club.
With three years left on his contract and the club's option to extend it by a further year, West Ham's owners are under no pressure to sell one of their star players any time soon.
While they may not want to sell him, due to the financial power Manchester United and Chelsea possess it could just be a matter of time before he is playing for either one of those clubs.
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