Juventus edged Monaco 1-0 thanks to an Arturo Vidal penalty while Atletico Madrid and Real Madrid finished goalless in the first two Champions League football quarter-final first-leg matches.
Champions League holders Real drew a blank at Athletico's Vicente Calderon stadium in a hard-fought meeting of the two sides who met in last season's final won 4-1 by Real in extra-time.
Real created the clear chances in a strong first half but Atletico fought their way back in an increasingly ill-tempered affair after the break.
Diego Simeone's side are now seven games unbeaten against Real this season, with the tie evenly balanced going into the second leg next Thursday at Real's Santiago Bernabeu stadium.
"It is not so good a result," Real coach Carlo Ancelotti said.
"We played really well first half and should score but we are happy for the performance. We have to try and repeat our first-half performance in our stadium."
In Turin, Vidal broke the deadlock when he scored from the spot in the 57th minute after a disputed penalty.
Monaco central defender Ricardo Carvalho clipped Alvaro Morato's heels when the two went for a lofted pass from Andrea Pirlo, and Vidal put the ball into the top right-hand corner from the spot.
Monaco started confidently and Gianluigi Buffon in the Serie A champions' goal twice had to get down to shots from Yannick Ferreira-Carrasco.
Carlos Tevez side-footed straight at keeper Danijel Subasic from a good position and Vidal fired well over the bar with the goal beckoning as Juve began to create opportunities.
Vidal however broke the deadlock when he scored from the spot after a disputed penalty when Monaco central defender Ricardo Carvalho clipped Alvaro Morato's heels when the two went for a lofted pass from Andrea Pirlo.
The contact may have accidental and also just outside the area, however Morato was undeniably denied a chance and Carvalho was shown a yellow card before Vidal struck the ball into the top corner from the spot.
Paris Saint-German play Barcelona, while Porto face Bayern Munich on Thursday in the remaining first-leg quarter-final matches.