This always looked a tough opening game against the side that finished second in Germany last season and so it proved. Although a Blues side without some of our stalwarts were pretty secure at the back in an opening half in which Daniel Sturridge went closest to opening the scoring, that was not so much the case in the second half and it needed captain-on-the-day Petr Cech to come out on top in a one-v-one with Michael Ballack for the visitors not to take the lead.
Once David Luiz had found the bottom corner of the Bayer net however, Chelsea were in the ascendancy on a night when it was shown that squad rotation is possible without detriment to our chances in Europe's number one competition.
It would be too easy to say David Luiz's strike so topping that is the ecstasy of a celebration that showed how pleased the exuberant defender was to be making a difference again. A thigh injury that kept him out since returning for pre-season training had left the Brazilian in the shadows but now the limelight returns. There was an acknowledgement of the part Fernando Torres played.
In four changes to the side that began against Sunderland, David Luiz played his first football of the season in place of John Terry and Florent Malouda replaced Frank Lampard on the left of midfield.
For Leverkusen, Michael Ballack started.
The restored Torres found the ball landing on his foot inside the penalty area with just a minute of the Champions League season gone. Sturridge was the supplier but the recipient had his back to goal and did well to hook a dropping ball goalwards. It went over.
Then came a tale of two disallowed goals, one at each end. First Leverkusen put the ball over the line at the far post but Mikel had been fouled in the build up. Then a move of class from Chelsea saw Mata strike the ball in from wide, Torres flick it on with his foot and Meireles continue the trend of back-heel finishes, but he was rightly flagged offside.
Torres was booked on eight minutes for the type of challenge on Leverkusen centre-back and captain Rolfes that often gets punished in Europe. Moments later Torres was found by compatriot Mata inside the area again but after taking a touch past a defender, the German side's keeper Leno saved the shot with a dipped arm. The 19-year-old between the visitors posts would perform well throughout the game.
There was almost a goal out of next to nothing when Ivanovic's long punt forward was punched out with two fists straight onto the head of Malouda but from a long way out, the Frenchman's hurried header went wide.
Chances proved harder to find in the middle part of the half as Leverkusen settled. Ballack's endeavour won a couple of free-kicks in the Chelsea half but there was little threat to Cech.
Then a mistake by Castro gave Malouda the ball in the danger zone. However Torres's control when a quick pass came his way was loose and although he kept possession, the space had disappeared and he was crowded out as he drove towards goal.
On 31 minutes, Sturridge took possession out wide and as everyone was expecting the cross, he unleashed a surprise left-foot crack at the target to which Leno had to react quickly to claw it away from the bottom corner of his net. It was looking like a moment of inspiration like that might be required to break down last season's Bundesliga runners up, although they weren't without mistakes in defence tonight.
For a minute the game became one of counter-attacks, Malouda giving the ball away but Meireles's sliding challenge halted a dangerous run by Kiessling. David Luiz sent Chelsea on the attack but Torres's cross was well defended.
Castro was booked for reacting badly when a free-kick was given against the Leverkusen full-back as half-time approached and then Sturridge went close with a shot from outside the area after Meireles had taken a free-kick with Leverkusen unprepared.
With the last action of the half, Ivanovic headed a Mata free-kick but it was easy for the keeper to claim.
Leverkusen started the second 45 minutes on top but when a Mikel clearing header dropped Ballack's way, he volleyed it back high into the Shed Upper. It was not the end of the chances for the former midfielder of this parish.
Chelsea changed shape briefly, Mata playing behind Torres, and a great David Luiz pass got his side attacking again and the crowd going once more, but Leverkusen came back strongly.
Schurrle was able to find the space in the area to drill a shot past the post and then after Chelsea had lost the ball in our half, it was played forward to Ballack. The 34-year-old was suddenly in front of goal and had the best chance of the game so far, but Cech blocked as he so often does and the rebound fell safely.
That was not the end of the visitor's chances and now Cech was truly earning his keep, saving from Schurrle after another passing move through our defence.
Amongst all that Leverkusen attacking, Torres headed a Malouda cross firmly down but Leno saved it on the line.
Chelsea also hit woodwork before the goal eventually came. It was Sturridge's shot that proved too hot to handle and Leno scrambled it against the post.
The two managers began to make changes. Anelka and Lampard were introduced and Ballack's evening came to an end.
David Luiz's earlier booking for pulling back Schurrle had been long forgotten by the time he both began and finished the 67th minute move that led to the breakthrough goal.
Driving forward into the German half, the Brazilian slipped the ball out to Cole and then was in position to take Torres's lay-off and dispatch the ball into the far bottom corner from the edge of the area. It was a sweet, sweet strike.
Mata's curler was creeping inside the post for a second goal soon after before Leno caught it with two hands, and the Spaniard fired on target again but this time the keeper tipped it over.
The chances were all Chelsea's in the closing stages, Lampard warming Leno's hands and a foul ruling out a goal when Anelka headed in.
With the final whistle just seconds away, Chelsea made the most of space down our left and Torres, with his second assist of the night, squared the ball for Mata to knock it past an exposed Leno.
Chelsea (4-3-3): Cech (c); Bosingwa, Ivanovic, D Luiz (Alex 75), Cole; Meireles (Lampard 64), Mikel, Malouda; Sturridge (Anelka 64), Torres, Mata.
Scorers David Luiz 66, Mata 90+2.
Unused subs Hilario, Ferreira, McEachran, Kalou.
Booked Torres 8, David Luiz 58.
Leverkusen (4-2-3-1): Leno; Castro, Reinartz, Toprak, Kadlec; Bender (Balitsch 79), Rolfes (c); Schürrle, Ballack (Augusto 65), Sam (Derdiyok 72); Kiessling.
Unused subs Yelldell, Friedrich, Bellarabi, Schwaab.
Booked Castro 38, Bender 71, Derdiyok 75.
Referee Stephane Lannoy from France