The USMNT international scored his first Premier League goal of the season in last Saturday's 3-1 win over Leeds, coming off the bench to make only his fifth appearance in the competition due to lingering hamstring problems.
Pulisic sustained the original damage in August's FA Cup Final defeat to Arsenal and Lampard has previously suggested the 22-year-old could be put on a specifically tailored training programme in an effort to reduce a susceptibility to injury which was evident prior to his £58 million move from Borussia Dortmund last summer.
Chelsea travel to Everton on Sunday and ahead of that match, Lampard said Pulisic was not 100% fit but could still have risked him in Tuesday's Champions League draw with Krasnodar had the circumstances been different.
"Christian Pulisic had a tiny bit of awareness off the back of the Leeds game with one of his hamstrings but he was training normally so we should be as we were [with players available to play Everton]," Lampard said. "With Christian, it is a work in progress.
"I don't want to call this an injury that he had in midweek. If the game had been a different type of game, it may have been one where I would have felt I would have used him.
"We know his abilities, that's very clear. He showed them when he came on against Leeds last week. I just have to find the right way to get the best out of him regularly and consistently."