Paul Merson believes Manchester United fans should be worried if Cristiano Ronaldo doesn't score against Newcastle in his second debut and feels Juventus wouldn't have sold him if they still believed he was good enough.
Ronaldo completed a sensational return to Old Trafford on deadline day, signing a two-year contract with the Reds to come back to Manchester 12 years after leaving.
While fans and pundits are excited to see Ronaldo make his second debut against Newcastle, Sky Sports pundit Merson believes the signing is not a guaranteed success and his performance on Saturday should set the tone for his season.
"He's just not going to be that player who beats players," he told Soccer Saturday.
"You watch him when he was at Man United before he was extraordinary, the stuff he was doing with the stepovers and what not. He was that good. He will score you goals if you put the ball in the box, my problem is [Marcus] Rashford, [Mason] Greenwood and [Jadon] Sancho are not playing when they're all fit.
"They're three very talented footballers, they're the future of Man United. I know they're going to learn off this man but at the same time, Ronaldo needs crosses in my opinion. We see that against Republic of Ireland, put the ball in the air and the man is a finisher.
"They play with two wingers who don't cross the ball. They play with Sancho who wants to cut inside and have a shot and play one-twos, they play with Greenwood on the other side who really wants to come inside or go outside and have shots.
"They're playing Newcastle today and if [Allan] Saint-Maximin gets going it could be a problem. It's a hard game. Newcastle are not turning up here and saying lets write this game off and we'll play in the next one, that's what they do in the other countries.
"I can't wait to watch him today. He has to score today, if he doesn't score today it's a problem. It's a prime game, this is the game. If I could pick a game this is one of them, Newcastle at home."
United agreed a deal with Juventus for an initial £12.8m to bring the Portugal legend back, and Merson believes the Serie A giants only agreed to let him go because they don't feel he can win them the Champions League.
"They didn't even win Serie A last season and they didn't even look like winning the Champions League. That's what he was brought in for.
"People are telling me they sold him because they couldn't afford him, they're a wealthy club. If they knew they were going to win the Champions League or had a chance then Ronaldo would still be playing there."
Sign up to our United newsletter so you never miss an update from Old Trafford this season.
