Chelsea s Romelu Lukaku takes the knee prior to the English Premier League soccer match between Crystal Palace and Chelsea at Selhurst Park, London, Saturday, Feb. 19, 2022. AP
Tuchel's side made a winning return to Premier League action after securing the Club World Cup in Abu Dhabi last weekend.
They took the points at Selhurst Park thanks to Hakim Ziyech's 89th-minute volley.
But it was Lukaku's anonymous display which was the centre of attention when Tuchel faced the media after the final whistle.
The former Inter Milan star's difficult season continued as he failed to make any impact.
He managed the fewest touches in a single top-flight game for a player who played 90 minutes since Opta started collecting data back in the 2003-04 season.
Lukaku had scored twice in the Club World Cup to reach 10 goals for Chelsea since his £97 million ($131 million) club record move to Stamford Bridge last year.
However, the 28-year-old has not netted in the Premier League since December, when he gave a controversial interview that featured criticism of the way he was being used at Chelsea and hints he wanted to rejoin Inter.
Tuchel opted against criticising Lukaku, but offered little defence of his latest flop.
"I am not so sure if I have a good answer to your question. I don't know what it says. It says he was obviously not involved and could not make a point. I am not sure if it says so much about us in general," Tuchel said.
"We look a bit drained, a bit exhausted, and you can see everybody tries hard. Everybody is looking for the flow where you try hard but nobody sees you are trying hard.
"We are looking for it but in this moment we struggle, which is not a bad thing because everybody wants to be part of it and everybody gives their best but we do struggle a bit.
"For that it is important to win and keep a clean sheet so we keep on going."
After beating Palmeiras to become club world champions, Chelsea had a full week to get ready for the trip to south London, but Tuchel insisted preparation was far from normal.
Cesar Azpilicueta and Callum Hudson-Odoi sustained injuries in training on Friday and it contributed towards a disjointed performance.
"You have no idea how a week like this works because we come from a 30 degree temperature difference, we have six players who have a cold from the AC (air conditioning) on the plane," he said.
"We have jet lag that the guys have, no players who slept well in Abu Dhabi because of the temperature and the time difference.
"If you think we have a normal week to prepare, I can tell you it is not like this."
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