The Germany international is understood to have informed Leverkusen of his desire to join the Champions League-guaranteed Chelsea, with reports stating he wants a move as soon as possible.
Leverkusen remain adamant Havertz will not move before the end of their Europa League campaign, however, which will now continue against Inter Milan on August 10 in Germany.
It didn't take long for the prolific youngster to show his quality, with his left-footed volley from the edge of the area clipping the bar just 15 minutes in with Rangers keeper Allan McGregor beaten in his top-left corner.
Havertz - primarily operating off the right flank, regularly drifting inwards - was presented with a glorious opportunity less than 10 minutes later. The youngster timed his run to perfection, but shot wide in a one-on-one he really should have buried.
His first-half contributions weren't done there, however; and this time, it wasn't in front of goal. After switching over to the left-hand side, he drifted inwards before floating an inch-perfect ball over the top for Moussa Diaby, who volleyed high and wide.
Havertz then showed he also possesses pace alongside his technical ability, racing down the right-hand side, before seeing his low cross crucially cleared.
In the end, it was Diaby who gave Leverkusen the lead in the 51st minute, with the German club subsequently strolling to victory.
Havertz did have one final opportunity before the game's end, as he tried to give McGregor the eyes to finish from the acutest of angles. His shot rifled into the side netting, but the confidence in his attempt was notable nonetheless.
Though failing to register a goal or assist, there was plenty to admire about Havertz's work. Primarily, his versatility is impressive.
Clearly capable on the right, left and up top, the youngster would improve Chelsea in a number of departments.
And that will be particularly useful for Lampard, with Pedro heading to Roma this summer while Willian looks to be on his way to Arsenal.
With Olivier Giroud - who Lampard favoured over Tammy Abraham towards the season end - now approaching 34, the arrival of Havertz along wit Werner would provide Chelsea a burst of youth and an abundance of attacking options.
Chelsea scouts likely get another glimpse of Havertz against Inter on Monday. And in a game where the youngster certainly wasn't at his best, he still showed just why Chelsea are so keen.