Ibrahimovic and Ronaldo go head-to-head for supremacy in Italy
Manchester United dominated for much of this lively Champions League last-16 clash but had to settle for a goalless draw with Inter Milan at the San Siro.
A Cristiano Ronaldo bullet header was well saved after four minutes and Ryan Giggs then missed when clean through.
Inter were much-improved in the second half as Zlatan Ibrahimovic burst to life, and after dummying for Adriano the Brazilian shot tamely wide.
A new-look United defence stood strong as Inter pushed for a late winner.
Old adversaries Sir Alex Ferguson and Jose Mourinho started the week by trading friendly jibes, with the United boss disputing claims his side would play defensively, emphasising the importance of away goals.
With Nemanja Vidic suspended, and Gary Neville and Wes Brown injured, Ferguson's hopes of improving on a measly record of one win in 12 games against Mourinho rose slightly with Jonny Evans and John O'Shea declared fit an hour before kick-off.
But the Inter boss, without Patrick Vieira, Marco Materazzi and Walter Samuel, might have felt vindicated on hearing that his opponents were leaving Wayne Rooney on the bench with Dimitar Berbatov playing alone up front.
However, if either team was guilty of playing cagey football it was Mourinho's side, who were off the pace for much of the first half.
With Giggs and Michael Carrick dominant in the middle in the opening exchanges it was the visitors who settled the quickest, with Ronaldo in the thick of the action.
The Portuguese winger had already gone close with a free-kick, and after four minutes his rocket header from a Giggs corner was brilliantly saved by the left arm of Julio Cesar.
While Inter's attackers were struggling to make friends with the ball, their defenders were faring little better and were lucky to get away with a Giggs through-ball to Berbatov, who failed to cross to the unmarked Ji-Sung Park.
A shockingly-timed Nelson Rivas tackle then allowed Giggs to squirm his way though again but the Welshman could only blast the ball at the over-worked keeper.
The home support became increasingly agitated as the sea of red piled forward, with Ronaldo just inches away from opening the scoring with yet another free-kick. He then headed just wide.
Ibrahimovic, misfiring until the 40th minute, pulled the ball back for Adriano but Edwin van der Sar sniffed out the danger. The Inter bench even got in on the action just before the interval as reserve keeper Francesco Toldo was booked for dissent.
The Inter manager was the first to change tactics, the Colombian Rivaz making way for Ivan Cordoba, and it seemed to rouse his team.
Esteban Cambiasso crossed from the left and, after an Ibrahimovic dummy, Adriano's shot flew high and wide.
The Brazilian was soon shouting for a penalty but his theatrics that followed a Rio Ferdinand hand on his shoulder did not fool the referee.
Wayne Rooney clashes with Esteban Cambiasso in the final few minutes
The Italians were much better and more composed in the second half with the menacing Cambiasso pushing the United defence regularly onto the back-foot.
Mario Balotelli and Julio Cruz were thrown on for Inter, but the Old Trafford side were not content to sit back with Ronaldo pulling back for Park, whose sliding legs just avoided the ball.
Giggs, once again on imperious form, went on a dazzling run, only to be thwarted by a lunging blocked tackle by Cordoba on the penalty spot and then Rooney, on as substitute with five minutes left, was denied by the legs of Cesar.
After Cordoba had brought Ronaldo down on the edge of the box in injury time and the Portugal star strolled up to take the free-kick, you sensed the headlines may be his.
But the ball flew safely within range of the impressive Cesar and so Old Trafford awaits for battle to recommence in a fortnight.
Although United cannot celebrate an away goal, they can take pride in increasing their unbeaten Champions League run to 20 matches and breaking the record they shared with Ajax and Bayern Munich.
Inter Milan: Julio Cesar, Maicon, Rivas (Cordoba 46), Chivu, Santon, Zanetti, Cambiasso, Muntari (Cruz 76), Stankovic, Ibrahimovic, Adriano (Balotelli 77).
Subs Not Used: Toldo, Maxwell, Figo, Burdisso.
Booked: Toldo, Chivu, Maicon, Cordoba.
Man Utd: Van der Sar, O'Shea, Ferdinand, Evans, Evra, Fletcher, Carrick, Giggs, Park (Rooney 83), Berbatov, Ronaldo.
Subs Not Used: Foster, Nani, Scholes, Fabio Da Silva, Gibson, Tevez.
Booked: Fletcher, Rooney.
Ref: Luis Medina Cantalejo (Spain).
BBC Sport Player Rater men of the match: Inter Milan's Julio Ceasr on 7.86 (on 90 minutes).
Please note that you can still give the players marks out of 10 on BBC Sport's Player Rater after the match has finished.
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