The American was introduced in the 55th minute, with Chelsea trailing 1-0.
Within 5 minutes, the 21-year-old scored the equaliser, and a couple of minutes later, Giroud netted the winning goal.
The boss asked Pulisic to use his talents to change the flow of the game, and the player succeeded in it.
Christian Pulisic has spoken after becoming one of the heroes for Chelsea in a difficult 2-1 win over Villa, as the American’s appearance as a sub helped the Blues come from behind.
“I’m really glad that I could come in and help the team in any way I could. Luckily today it was with a goal and it helped us get a good result,” he said Sky Sports.
“He (Lampard) told me to go in and help the team win the game, use my skills and do what I could do, and I’m happy I could do that.
“I don’t think I hit it perfectly with my left foot, luckily I got enough on it to steer it on target so I’m happy it went in.”
The win allowed Chelsea to increase their advantage over Man United and Wolves to 5 points with 8 games to go. Now, Chelsea are firmly in the front seat for the Champions League place.