(CNN) -- Jose Mourinho drew first blood in his battle with old adversary Alex Ferguson as Serie A leaders Inter Milan denied Manchester United a vital away goal in their Champions League first leg clash at the San Siro on Wednesday.
Van Persie celebrates his successful penalty in Arsenal's 1-0 win over Roma.
In the night's other England versus Italy encounter Robin van Persie gave Arsenal a slender lead from the penalty spot in their last-16 clash against Roma at the Emirates.
World Player of the Year Cristiano Ronaldo was frustrated on several occasions by Inter including the last strike of the match from a free kick than thudded into Brazilian goalkeeper Julio Cesar's chest as the sides ended goalless.
Ferguson must now achieve something he has managed just once in 13 meetings and defeat Mourinho in the return.
The United supremo praised his side's performance, telling ITV1: "We played very well. In the second half, for 10 or 15 minutes, they presented a bit of pressure which we expected but other than that we played very, very well, with good composure and maturity.
"I think we're playing very well at the moment, it doesn't matter who we are playing against. Tonight they showed expression, they enjoyed playing the game and that showed maturity."
As for his side's failure to score, the Scot added: "I just hope it doesn't come back to bite us. At Old Trafford on the night in a couple of weeks' time the atmosphere will be fantastic and I think we've got a great chance."
The speed of United's movement caught Inter napping almost as much as Ferguson's decision to leave Wayne Rooney on the bench -- although the England striker was booked during his substitute appearance.
Ronaldo, meanwhile, did his best to break the deadlock with a series of free-kicks while he also had a point-blank header that flashed wide.
Arsenal manager Arsene Wenger admitted he would have liked a bigger cushion to take to Rome.
"We played well," he added on ITV4. "There was room for more goals, that's the only regret from tonight. "We kept a clean sheet, that's important, and I felt every time we got the ball we used it well."
Dutchman Van Persie earned and converted a 37-minute penalty, but the Gunners should have had a second with Nicklas Bendtner and Emmanuel Eboue both spurning golden chances.
Asked if he thought Arsenal had done enough, Van Persie replied: "It's tight, it will be really hard (in Rome). I hope it will be enough."
The penalty came when Van Persie got into the left side of the area, and was tripped by Philippe Mexes. He stepped up to take the spot-kick himself and coolly dispatched his 15th goal of the season into the bottom right corner.