Chelsea got the better of Rennes 2-1 away from home in France in Group E on Tuesday evening.
Rennes restored parity in the 85th minute when Serhou Guirassy headed home from a corner.
However, Chelsea had the last laugh when France international striker Oliver Giroud headed home in the first minute of injury time.
The result means that Frank Lampard’s side are now at the top of Champions League Group E with 10 points from four matches, level on points with second-placed Sevilla.
With two more rounds of games left in the group stage this season, Chelsea are guaranteed a place in the top two and have booked their spot in the last 16.
Chelsea defender Azpilicueta has taken to Twitter to revel in the win and is delighted to have progressed to the last-16 stage of the Champions League this season.