The Argentine was signed by West Ham during the summer transfer window, and he has wasted no time making an impression at Upton Park.
Tomkins says that the 22-year-old is capable of being a match-winner, and he has been very impressed by the attacking midfielder’s showings so far.
"Manu has done brilliantly for us already this year, and he can change the game in a minute," Lanzini enthused.
"You can see what he did against Everton – that’s him every day in training.
"There’s people like himself and Mauro, and Andy, who offers a completely different threat."
Lanzini was one of very few West Ham players to come out of their defeat to Tottenham Hotspur last weekend with any credit.
Slaven Bilic’s side were beaten 4-1 by Spurs, but Lanzini still showed his class in the contest by netting a stunning late goal.
Lanzini’s next chance to impress is likely to come on Sunday, when West Ham take on West Bromwich Albion at Upton Park.