Newcastle United's Isaac Hayden left, and Chelsea's Willian compete for the ball.
Chelsea went six points clear in the chase for Champions League qualification by sending Newcastle into the English Premier League relegation zone on Saturday.
While Willian's curling strike gave Chelsea a 2-1 victory over Newcastle, manager Maurizio Sarri was still unhappy with the laboured performance and fragility.
Pedro Rodriguez collected David Luiz's pass before netting to put Chelsea in front in the ninth minute.
"After the goal, I think we thought, 'Now it's easy,' but it wasn't," Sarri said. "We slept for 20, 25 minutes, so at the end of the first half we were in trouble."
Ciaran Clark equalized in the 40th minute after leaping to reach Matt Ritchie's corner and heading past goalkeeper Kepa Arrizabalaga.
But Eden Hazard set up Willian for the winner in the 57th as Chelsea quickly recovered from losing the first leg of its League Cup semifinal to Tottenham. It allowed Chelsea to take advantage of fifth-place Arsenal losing at West Ham and move six points clear to strengthen its hold on the fourth and final Champions League qualification place.
Newcastle fans chanted against owner Mike Ashley, with the northeast English team a point from safety in the relegation zone.
"Hopefully everybody can see the effort is there, we're trying our best and still it's not enough," Newcastle manager Rafa Benitez said. "We have to stay calm. It's a long-distance race."
