The United States international sat out Sunday's showdown with Liverpool in the Premier League, as he watched on from the bench for the entire 90 minutes in a 2-1 loss for the Blues.
The 21-year-old has made three Premier League starts since arriving at the club this summer, although his previous one came in the 2-2 draw with Sheffield United on 31 August.
"I have a squad to pick from; I decided to go with Mason [Mount] today," the former Chelsea and England midfielder said. "These are my choices to make. Christian is a young player as well. His chances will come. There are people on the bench."
Chelsea fell behind in the first half of the encounter, with Trent Alexander-Arnold and Roberto Firmino on target for the visitors. N'Golo Kante gave the Blues hope of a comeback in the second half when he found the net, but they were unable to snatch an equaliser.
Lampard may have called on Pulisic late in the game as his team pushed forward, but he was forced into making unforeseen changes early in the match which restricted his options. Both Andreas Christensen and Emerson hobbled off injured before the interval.
The Men In Blazers podcast were disappointed not to see the American tyro get on the field for the game:
Miguel Delaney of the Independent speculated as to why Lampard may not be calling on the winger more often:
While the result was a disappointing one for Chelsea, the manager would have been pleased with the manner in which his team played.
Despite coming up against a strong outfit in Liverpool, they were spirited and determined in their attempts to get back into the game. In attack, Mount and Tammy Abraham have been major threats throughout the campaign, and both were involved in Chelsea's best attacking moments against the Reds.
Per Nizaar Kinsella of Goal, the biggest issue that faces Lampard at the moment is keeping opposition teams out:
Chelsea get their Carabao Cup campaign underway on Wednesday against League Two Grimsby Town, and they will be looking to go one better than they did a year ago when they finished runners-up in the competition to Manchester City. Pulisic should start that match at Stamford Bridge.
Although there's plenty of excitement about Pulisic, it's understandable Lampard is taking time to integrate him into the side. The Chelsea boss has already drafted in a number of young players, and he will be wary of leaving the team devoid of key experience when it comes to facing elite opposition.