The 19-year-old has hit the ground running with the Red Devils in the weeks following his big-money transfer from the Ligue 1 outfit in September.
Martial has been a regular in Louis van Gaal’s first team since his arrival at the club and has already scored four goals for the Premier League outfit.
The teenager will be hoping to feature when United host local rivals Manchester City at Old Trafford in the Premier League on Sunday afternoon.
And former Liverpool midfielder Redknapp has been thoroughly impressed by what he has seen from the forward since his arrival in England.
Redknapp told Sky Sports: “The addition and impact of Anthony Martial has transformed Manchester United’s situation this season.
Before he came to the club, I didn’t put them anywhere near mounting a title challenge. Nowhere near. Now, if they beat Manchester City, they will believe they can do it.
“There’s no excuse now. Louis van Gaal has had a good amount of time to look at their situation, they’ve spent a lot of money and the start they’ve made, although it hasn’t been spectacular, suggests there is enough there to have a real go at it.
“But, make no mistake, Martial’s introduction has been key. The pace, athleticism and skill he possesses, along with the goals he’s scored, is incredible. He’s been the catalyst behind United doing well, more than anything else.
“Because he’s so young, whether he can do it over a sustained period, we’ll see. But he’ll be a key factor this weekend.
“Against Everton, Van Gaal used him on the left wing, partly to contain Seamus Coleman. On Sunday, Martial will come up against Pablo Zabaleta, who, like Coleman, plays so high up the pitch.
“I was happy to see Martial used in that way against Everton, but at home to City, Van Gaal needs to think how he can use the Frenchman to cause their visitors problems, rather than how he can contain their attacking threats. If he plays wide, that will be a key battle in the game.”
Van Gaal’s United head into Sunday’s showdown in third place in the Premier League table and two points behind leaders City. A win would move them above their local rivals.
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