The United States international missed the start of the season but was looking set for a run in the Chelsea side until he suffered a twinge in the warm-up before the October 31 match at Burnley.
The £58million signing from Borussia Dortmund has been ruled out of Saturday's trip to Newcastle United, three weeks after his Turf Moor setback was described by Lampard as "very minor", and it remains to be seen when he will be next available for selection.
There is no doubt the situation is frustrating to all concerned at Chelsea, with the club's medical staff working to help Pulisic back to full strength.
"With Christian, we're still searching," said Lampard. "He's in a position at the moment where he's had a problematic injury.
"Christian had a history before coming to us of some muscular injuries and he's had them again.
"Everything about Christian and how he is around the training ground, and how he prepares and how much he wants to play, is perfect.
"We need to try to find the right balance between playing and resting and maintenance during the week to try to get the best out of him.
"He's a young player still. It's not abnormal and we will find a solution. I don't want to make more of it than it is, because we want as many games out of Christian as we can possibly get because of his ability.
"But at the minute he's injured so in the short term it's a work in progress.
"But we have a great medical team here and we're very much joined up in the idea of getting the best of Christian, to get him fit as much as we can."
HOW IMPORTANT HAS PULISIC BEEN SO FAR?
Given the stop-start nature of his Chelsea career, it could be some time before we get the full picture of what the 22-year-old will bring to the Blues.
He has made just three Premier League appearances in the 2020-21 campaign, while last season's figures illuminated his threat but were inconclusive in a wider sense.
Although Pulisic scored nine goals in 25 league outings, of which just 19 were starts, Chelsea's results were stable whether he was in Lampard's XI or not.
Of those 19 games that he started, Chelsea won 10, drew three and lost six, and their record was identical for the 19 games that Pulisic either sat out or appeared as a substitute.
With him in the starting team, Chelsea scored 32 times and conceded 26, while without him from the first whistle they netted 37 goals and shipped 28.
Pulisic has great attributes, with his pace, dribbling and eye for a strike, but Chelsea are the Premier League's top scorers with 20 goals this term and he has not contributed to that tally, or had an assist.
He did score in the Champions League win at Krasnodar, after coming off the bench, but injury struck three days later.
Lampard naturally wants the USA star back in his matchday ranks, but Chelsea have found a way to flourish without him.
WAS IT ALWAYS THIS WAY WITH PULISIC?
As Lampard says, Pulisic is no stranger to an injury, but Chelsea plainly bought a class act. Opta data tells us that Dortmund were more prolific with Pulisic than without him in 2018-19, his final year at the club.
When he started in the Bundesliga - albeit just nine times in that season - they averaged 3.0 goals per game compared to 2.2 without him in the line-up, while their goals against figure held steady at 1.3 whether he was selected from the off or not.
In the games where Pulisic started, the numbers of shots and crosses per game, as well as passing accuracy in the opposition half, all climbed.
In the 20 games in which he played a part, Dortmund won 14, drew four and lost twice for a points-per-game average of 2.3, while that dipped to 2.1 when he was absent.