City have shipped six goals in their last two matches, having also lost 3-2 to Manchester United at the weekend - the first time that has happened to a Guardiola-managed side.
The Catalan coach went with Vincent Kompany and Nicolas Otamendi for both games, but he is now tempted to bring in either John Stones or Aymeric Laporte for the return fixture with Liverpool at the Etihad Stadium.
"Maybe, I have an idea what we have to do tomorrow, what the guys are going to do," he said at his pre-match news conference. "But in the case of Nico, when a player does what he has done, all we can do is to be close to him because Nico is not just a huge quality but a huge mentality.
"It's true the third goal [against United] he has to defend his back, but we are here in the quarter-finals and 13 points in front in the Premier League and Nico is an important reason why."
Asked about Stones's recent omission from the starting lineup, Guardiola replied: "After he had an injury in the national team [in November] when it was six, eight weeks off and after coming back he had little problems with the confidence.
"In the last game with the national team he had a concussion and he could not play in Everton, he was seven days without a training session, and before United he felt something in his adductor.
"He was not perfect and I decided not to take a risk. He knows the confidence I have in him, especially in the last years. He has to fight with these guys to prove why he should play."