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But Giroud, who came on as a second-half substitute, would have the last word as he netted a header in stoppage time to give Chelsea a 2-1 win.
The 34-year-old has grown frustrated at his lack of minutes at Stamford Bridge this season, as he's made just one total start and played only 36 minutes in the Premier League.
The play of Timo Werner and Tammy Abraham has helped keep Giroud on the sidelines, with the France international looking for a move in January to gain more minutes ahead of Euro 2020.
In his press conference after the game, Lampard saluted Giroud's professionalism during what has been a difficult period.
"The things behind the scenes, everybody kind of feels from the outside to be fair what a great professional he is and how highly regarded he is by his team-mates and myself," Lampard said.
"So for him to get a goal, you saw the reaction of his team-mates, he's so professional in how he trains and looks after himself that age isn't even a factor for him. He's getting better with age if anything in terms of how he looks after himself.
"So he offers a lot for us and I keep saying it but the big schedule coming up and the way we play means I will rely on players. So thankfully for me he's a player that always keeps the right attitude if he's not playing regularly, and I know when I call upon him that he comes in as he did today."
As Chelsea get set for a busy December that will see them play eight matches, Lampard has stressed the importance of Giroud to his plans.
"It is selection issues for me," Lampard said. "We need that. We need that with playing every three days, maybe at Christmas we are playing every two days unless the schedule gets sorted out.
"With Oli, it is hard to say I have to prove it to him. I have to look at it game by game and play him to get the best for us. At the moment, Tammy is in great form as well. I think Oli knows how much I am happy with him. I hope he knows how much I rely on him.