Tuchel decided to name Silva and Kante among Chelsea’s substitutes against Porto at the Ramón Sánchez Pizjuán Stadium in Spain.
The German said he left Silva on the bench because the Brazilian defender was not yet at full fitness after being denied the chance to earn 90 minutes against West Brom in the Premier League last Saturday.
According to him, he left Kante on the bench because he wanted Chelsea to play quick and fluid attacking football against Porto.
However, Tuchel eventually featured Silva and Kante late in the second half of the encounter as the pair replaced Reece James and Mason Mount, respectively.
“He [Thiago Silva] only had half an hour [against West Brom], and all the other guys are totally fit, so it’s not the moment to improve your fitness level in a quarter-final,” Tuchel told BT Sport.
“We trust the guys and we are clearly aware that we need a 100 per cent physical level. Thiago is a super important player but is not fully fit for 90 minutes at the highest level, and we decided for the back three.”
Comment on Kante, Tuchel continued: “It’s not a blow at all, we have him [Kante] on the bench, and I am delighted about that. He gave the green light yesterday much quicker than expected, so we are absolutely happy to have him on the bench to finish the game for us.
“It’s about running, attacking the box, it’s about being quick and fluid in our attacks. That’s the target for our front three guys, we decided for them because it’s very difficult to create chances against Porto, it’s very difficult to score goals, so it’s a big task, but it’s always the aim in football.
“It is a team effort to attack, it is a team effort to defend, and we went with this line-up with full confidence and full trust.”
Meanwhile, goals from Mason Mount and Ben Chilwell ensured Chelsea defeated Porto 2-0.
