Yaya Toure conceded he is "a little bit scared" for Manchester City in their Champions League last-16 encounter with Real Madrid.
City went through their group stage unbeaten, winning four of their six games and scoring 16 times as they topped a pool featuring Atalanta, Shakhtar Donetsk and Dinamo Zagreb.
However, Pep Guardiola's side were then handed possibly the sternest test possible as they were pitted against 13-time winners Madrid, who only finished second in Group A behind Paris Saint-Germain.
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Madrid have never lost a Champions League knockout tie under Zidane, who won three successive trophies during his previous reign and returned last March, with Los Blancos' European pedigree leaving Toure fearful for his old club City.
"I wanted City to get Lyon or some club like that, but Real Madrid is going to be a tough game, a very, very tough game," Toure told Omnisport.
"But we will see - the first game is at the Bernabeu and then it is [at the] Etihad [Stadium].
"Real Madrid could knock us straight out. They could, they really could, because we expect Real Madrid to be in the quarter-finals, the semi-finals and now they face City.
"I'm a little scared to be honest."
The first match takes place on Wednesday, February 26, with Madrid then travelling to Manchester for the second leg on March 17.
Madrid were eliminated at the last-16 stage last season by Ajax, which prompted the club to turn back to Zidane.
The Frenchman has presided over a 15-game unbeaten run in La Liga and Toure was particularly impressed by Madrid in their 2-2 home draw with PSG in November, even though Zidane's side threw away a two-goal lead late on.
"The last time I saw a game is when they played against Paris Saint-Germain, it was very good," Toure added.
"Even though [PSG] take two goals in the end, Madrid was on top of Paris Saint-Germain and Paris Saint-Germain are a good, good side.
"I think Paris Saint-Germain is going to be going forward to the semi-final or final. We never know. They are playing very good, they have a good coach.
"I hope Man City are going to pass Madrid but this is a big, big test, a big ask."