Aurélien Tchouaméni has called criticism of Kylian Mbappé "incredible" ahead of Real Madrid's Champions League round of 16 second leg away at rivals Atlético Madrid on Wednesday.

Real go to the Metropolitano with a slim advantage, after beating Atlético 2-1 in last week's first leg at the Bernabéu, with goals from Rodrygo and Brahim Díaz.

Mbappé failed to score in an underwhelming display -- his third consecutive game without finding the net -- before getting back among the goals in Madrid's 2-1 LaLiga win over Rayo Vallecano on Sunday, to make it 29 goals this season in all competitions.

"It's incredible talking about 'difficult days' for [Mbappé]," Tchouameni said in a pre-match news conference on Tuesday. "Because he didn't score in two games? We know that if he scores a goal or two tomorrow, everyone will be saying 'he's an incredible player.' For us professionals, the most important thing is the next game. Kylian doesn't need advice, he's scored a lot of goals and he will score a lot of goals."

Mbappé is set to undergo tests on Wednesday after suffering a blow during the win over Rayo and failing to train with the team on Tuesday, though manager Carlo Ancelotti is hopeful the France forward will be passed fit to play, sources told ESPN.

The highlight of Mbappé's season so far came in the previous round, scoring a hat trick against Manchester City at the Bernabéu, before drawing a blank against Atlético.

"Honestly Kylian wants to win and score goals every game, so there's no extra motivation," Tchouameni said. "He wants to be at his best level all the time, there's no difference."

The midfielder has faced criticism himself, but has played some of his best football in a Madrid shirt in recent weeks.

"For me, the most important thing is the next game," Tchouameni said. "You can be the best in the world, but people will talk about your level, saying that they prefer other players. The most important thing is working and trying to improve all the time."

Ancelotti said he expected another tight game against Atlético, who have never eliminated Real in the Champions League.

"As far as I remember, every game against Atlético has been even and competitive," Ancelotti said. "Tomorrow will be exactly the same. It will be decided by small details, that's what has always happened."

Ancelotti praised Atlético coach Diego Simeone -- saying they "have a similar idea of football" and said Real wouldn't be overly focused on practising penalties in training, ahead of a possible shootout.

"In training, you can see which players shoot best," Ancelotti said. "But in a shootout, the mental aspect is more important than the technical one. If you aren't mentally ready, it can affect your technique. I've won Champions Leagues with defenders who scored penalties -- [Alessandro] Nesta, Serginho [with AC Milan] -- because mentally, they were well prepared."