Chelsea lie third in the division, currently two points behind leaders Arsenal, who could increase their advantage if they win away to Southampton on Tuesday.
But the Blues' seventh consecutive victory in all competitions -- a 1-0 victory against Stoke last weekend in the fourth round of the FA Cup thanks to Oscar's match-winner -- has enhanced the ever-increasing confidence at Stamford Bridge.
And Lampard, who skippered the team against the Potters, insists his team-mates, who have not lost at home under Jose Mourinho in a remarkable 72 fixtures, are developing the mentality required to win silverware come the end of the season.
"There's a good feeling around the place," said Chelsea midfielder Lampard.
"With the manager coming back it probably took a while for him to get his points across but, in the last couple of months we've found that mentality and feeling in the dressing room where we're going out there with more confidence.
"We have to keep that up because the minute you drop that the results will turn, so we need to keep at it and carry on this form.
"As a team, we were all at it against Stoke and we were disappointed not to be two or three up at half-time because we would have cruised it. But at 1-0, you have to keep on your guard all the way."
Following the derby showdown with relegation-threatened West Ham, Chelsea will test their title credentials with the trip to Manchester City, presently second, on Monday.
Chelsea will have to deal quickly with life after Juan Mata, who joined Manchester United in a £37.1 million ($61.2m, 44.8 million euros) deal last weekend -- a club record signing for faltering champions United.
But while Lampard was full of praise for his former team-mate, the England international said Chelsea had the quality to cope without the Spaniard.
"Juan Mata's an absolutely fantastic player and, more than that, he's a great lad, so I wish him all the best personally," Lampard said.
"The difficult thing here is that there are so many brilliant players.
"Oscar's been fantastic this season, as has Hazard. Willian's shown it as well and we've got so many riches in that position, but you need performances like the one we got from Oscar and his free-kick was top drawer."
Chelsea have scored 43 goals in the Premier League but the Hammers are averaging one goal a game from their 22 matches so far this term.
"We need somebody in that box to be productive and to start scoring goals, someone who only needs one or two chances," said West Ham manager Sam Allardyce. "At the moment we are needing six or seven.
"You have got to try and see light at the end of the tunnel and stay positive.
"The re-introduction of Andy Carroll and with the (signing) of Marco (Borriello) now, it should bring a bit more optimism to everyone at West Ham -- the fact that these players are coming back and that new players have signed on.
"There are some big games coming up and if we start to get on a bit of a roll, which is an undefeated run to begin with because not losing games is critical for us now, then hopefully we will start producing more goals and victories.
"We are top of the league in terms of quality crosses which suggests our finishing has been our Achilles heel this season."
Source : AFP