Frank Lampard believes Chelsea's trip to Watford is "more dangerous" because the Hornets have not won a Premier League game this season.
"I'm very much of the mindset that games become more dangerous with overconfidence," Lampard said. "We must understand Watford and their quality.
"Last season their personnel was similar and they were getting big results, they made the FA Cup final.
"We cannot underestimate a team that will be hurting because they have not won for a while. They will have every ambition to win this game, so I'm even more focused on what we need to do."
Chelsea will be without Antonio Rudiger, N'Golo Kante and Ross Barkley for the trip to Vicarage Road as the Blues attempt to bounce back from Wednesday's defeat to Manchester United.
"We made six changes, came up against a strong United team and I think in the first half it was pretty dour," Lampard added.
"In the second half we were the better team and without Rashford's wonder strike... the biggest thing I took from the game was that if you're not clinical enough - you need to take your chances."
When asked if he now had to pick between Pulisic and Callum Hudson-Odoi, Lampard said: "You could say Pedro and Willian as well, who are top-class players in different stages of their careers.
"There's competition for places. That's good. It keeps them on edge and means they have to perform to keep their place... I'm not here to rotate for the sake of it."