Werner made his Premier League debut for the Blues as they beat Brighton 3-1 at the Amex Stadium, with the Germany international winning the penalty from which Jorginho opened the scoring for the visitors.
Werner completed the rest of the game, but had an ice pack strapped to his thigh following the match and confirmed that his movement had been limited by Mat Ryan's challenge which led to the spot-kick.
Brighton equalised in the second half through Leandro Trossard's 54th-minute goal, but Chelsea were ahead two minutes later through a Reece James wonder strike before the full-back turned provider with a corner for Kurt Zouma to make it 3-1 with 24 minutes remaining.
Following the match, Chelsea boss Lampard praised Werner - and hopes that the 24-year-old's injury is merely a dead leg.
"I was really pleased with Timo," Lampard said. "I know the qualities he is going to bring, we saw that with the speed to get the penalty.
"He is going to be a real threat. He is a very mobile centre-forward who can do so many things for us. He is one who has had some games, he has a bit of fitness, and you could see that.
"He took a knock when he won the penalty which we hope is a dead leg. I would like to think if it is that we have a bit of time to get him back [for the Liverpool game]."
Christian Pulisic is expected to form an important partnership in attack with Werner, but the USA international missed out on Lampard's matchday squad due to injury.
"Christian was training with us last week but he had a bit of discomfort a couple of days ago when he was trying to be in contention for today," the coach confirmed.
"It would have been a big ask for today and he has had to take a few steps back and we will have to see."
As for Jorginho - who scored Chelsea's opener from the spot before assisting James - Lampard says the Italy international is, like a few of his players, still short of full match fitness.
"Jorginho is just tiredness," Lampard added. "A lot of players are not fully fit at the moment and that is just the way it is.
"I thought they dealt with the rigors of the game very well in terms of how tough it is to come to Brighton when you are not quite there."