Giroud, after admitting coming close to leaving Chelsea in January, penned a new 12-month deal with the Blues in May. After putting pen to paper, Giroud soon learned of Chelsea's swoop for Werner. The Red Bull Leipzig striker would arrive as a direct threat to Giroud's playing hopes.
Giroud says he first spoke with captain Cesar Azpilicueta about the situation and his concerns before choosing to approach Lampard.
And the veteran, now 33, admits he sought out Lampard for crunch talks about his future at the club and where he stood in the manager's plans.
He recalled to Bein Sports via Le 10 Sport: "Timo Werner? I provoked this discussion with the coach because I wanted to make him understand initially to be transparent with me that I had not made this end of the season when I scored 8 goals out of my 10 starts in Premier League for nothing.
"I fought to get back into the team after a transfer window where I was convinced to leave Chelsea. The coach gave me this chance to come back to the team and I took it. I did a good job, I discussed it with the guys including Azpi (César Azpilicuelta), it is thanks to my performances that the team was also able to reach the Champions League, and I was proud of it.
"Now it wasn't to leave at the start of this season, although I know the competition will be even tougher. I still want to believe in it and fight for my place. I know football can go fast. I was discussing it with him, it is true that the arrival of Timo is an additional motivation, therefore necessarily an additional competition knowing that he can also evolve on one side. He does it in the national team and in Leipzig too, he is more at ease with another striker, a true 9.
"So I spoke about it with the coach and since in recent matches he has played on the left, there will be healthy competition with Tammy (Abraham) at the forefront… But it's true that we have a lot of offensive elements.
"We will see how it evolves in the coming weeks."
So far this season, Giroud has featured three times for Chelsea, once in the Premier League and twice in the Carabao Cup, where he's scored once.
- updated Octoboer 5