Chelsea completed a £58million deal for Borussia Dortmund’s Pulisic in January 2019 while Maurizio Sarri was in charge of the club.
The USA international did not move to Stamford Bridge until the following summer when Lampard had replaced Sarri as manager.
Earlier in the month, RB Salzburg manager Jesse Marsch claimed Lampard doubted Pulisic’s ability to make an instant impact at Chelsea because of his nationality.
Marsch said: ‘Even Frank Lampard, when I spoke to him in pre-season a year ago now, I was talking to him about having Christian Pulisic and he was kind of like, “Yeah, he’s got a lot to learn so we’ll see how he does”.
‘I said to him, “Listen, he was at Dortmund, and they had a high level of tactical thinking, of playing, and he was very successful”.
‘I could see right away that Frank Lampard’s idea of Christian Pulisic was shaped a lot by the fact that he was American and not that his football education came a lot from what has happened in Germany.’
Lampard believes Marsch recalled the conversation incorrectly, however, and heaped praise on Pulisic for enjoying a ‘breakthrough’ season at Chelsea.
The Blues boss said: ‘I did read the comments, I was surprised that he had managed to read my mind as well as he thought he did.
‘He has recounted the conversation wrong and I have to put it correct. It was a game against Salzburg in pre-season and Christian scored two goals.
‘Jesse came up to me and we spoke about Christian. He said he was a talented player and I agreed with him and we spoke about how exciting his development will be.
‘I played in America for 18 months and I would never underestimate the desire that American players have to learn and to improve.
‘Christian has that desire and talent also so it was never in doubt for me. I understand the rigours of the Premier League.
‘It’s clearly the toughest league in the world and it’s not just Christian who would have felt that, but some of the greatest players in history have.
‘What Christian did was find his feet very quickly and have a breakthrough season with lots of goals and assists.
‘His performances were massively impressive and he will get better and better. I never doubted that.
‘I’m not jumping on Jesse but as a manger I never doubted Christian and it’s important for me to put that straight.’
Lampard’s Chelsea thumped Krasnodar 4-0 in the Champions League on Wednesday and return to Premier League action on Saturday against Burnley.