"The second half was a bit too open, maybe, but Isco had a wonderful game in all aspects, on and off the ball sacrificing himself".
Juventus still went on to win 2-0 at Valencia, thanks to two penalties.
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It was the 11th red card of his career, but his first in 154 Champions League matches.
Amid a hostile atmosphere, opposing players clashed in the box and the referee spoke with his assistant at length before producing a red card.
On a disastrous night for Real as they lost a Madrid derby for the first time in 14 years, Ronaldo kicked out at Atletico captain Gabi in the final few minutes and was shown a straight red.
Allegri said: 'The lads did really well as we had numerous chances even before Ronaldo's dismissal, then we deservedly took the lead. I gave him loads of assists and he doesn't need me to remind him of that!
In the other Group F game earlier on Wednesday, Brazilian youngster Maycon came off the bench to rescue Shakhtar Donetsk a 2-2 draw in their game against group-stage debutants Hoffenheim in Kharkiv.
Finally, in group H, Valencia will entertain Italian Serie A title holders, Juventus, and Swiss side, Young Boy, will welcome Manchester United. "We risked losing tonight and now we can only hope he is not banned for long". Although Valencia were handed a penalty in injury time after late substitute Daniele Rugani fouled Gabriel, Parejo's weak effort was saved by Szczesny.