Silva, who usually operates as an attacking midfielder, featured in a deeper role with Rodri and played a vital part in City's victory at Stamford Bridge as they moved up to second
Asked at the pre-match news conference what it was like to have to break his selection news to the players, Guardiola said: "Terrible. It's absolutely disaster, don't be a manager in your life."
The Spaniard said there were no words that he could conjure up to ease the pain for the players concerned.
Aguero has won 12 major trophies with City -- including the club's first Premier League title in 2011-12 when he scored an injury-time winner on the final day of the season.
"Tomorrow we'll decide," Guardiola added. "As much he can play he will play. He's been disrupted, he had a partial training session."
"Let me try to win at Crystal Palace... United is an extraordinary team arriving in the last two months in their best form of the season and we need five points to be champions," Guardiola, whose side beat Paris St Germain 2-1 in the Champions League in midweek, told reporters on Friday.
"All we can do now is recover as well as possible from the physically and mentally tough game we played in Paris. It is our sixth game in a row away. It is a lot of travel and we are tired in many aspects.