The 19-year-old burst onto the scene in February, hitting a brace in United's 3-2 win over Wenger's side just days after scoring twice on his first-team debut against FC Midtjylland.
Rashford has now established himself in Jose Mourinho's squad, starting the last six Premier League games for the Red Devils.
And he is likely to start as United's main striker at the weekend, with Zlatan Ibrahimovic suspended and skipper Wayne Rooney expected to only be fit enough for the bench.
Asked about Ibrahimovic's unavailability, Wenger instead focused on the man who will be looking to prevent Arsenal getting their first league win at Old Trafford in a decade.
"Certainly they would prefer to have him (Ibrahimovic)," he said.
"But we have as well players out and let's not forget, last year the guy who killed us was Rashford
So let's not speculate on any weakness of Man United."
The Frenchman, who goes in search of his first-ever Premier League win over Mourinho having failed to better his adversary in 11 previous meetings, also admits Rashford's impact came out of the blue last season.
"Yes of course," he replied when asked if Rashford had taken him by surprise.
"Maybe a bit less, because I watched him against a Danish team in midweek and he scored and I could see straight away that this guy could be dangerous.
"On crosses his movement was good, the way he moved in the box was strong
he took everyone by surprise because no one knew him in England."
With records seemingly against Wenger, he has been keen to point out the 3-2 loss nine months ago - albeit damaging to Arsenal's ultimately forlorn title ambitions - remains their only defeat away from home in the league in this calendar year.
"In 2016 we lost one away game in the whole year and that was at Old Trafford," he added.
"So overall, on top of that, I think that is really the key game, it was a key game for us and that is where we did not respond with the quality of performance on the day.
"We did not only lose the game, but that's maybe one of the few away games in the whole year where the performance was not at the level.
"So we want to focus on that and respond with a strong performance and after we have to accept the result
But what will be very important for me is that we respond with a strong performance on Saturday morning."
Wenger will assess the fitness of forward Alexis Sanchez ahead of the game after he returned from international duty with Chile on Friday morning.
The 27-year-old has hit eight goals for the Gunners this season but, having scored twice for Chile in midweek despite carrying a hamstring injury, he could yet be forced to sit out the lunchtime kick-off.
Hector Bellerin is definitely out after injuring his ankle in the 1-1 draw with Tottenham ahead of the international break and joins Santi Cazorla, Lucas Perez, Per Mertesacker and former United striker Danny Welbeck in missing the trip to Old Trafford.
Source : PA
Source: PA