Eden Hazard and Olivier Giroud both return to the starting eleven for Chelsea as they face BATE Borisov away in the UEFA Europa League. After the match Sarri said he was far more satisfied with three points than his team's performance.
Dmitri Baga had hit the post in the first half from long range and Nikolai Signevich followed sit on the hour mark.
Both sides were the beneficiaries of comical own goals in a insane first half which ended with Glenn Middleton putting the Scots 3-2 ahead, but Luiz Adriano and Sofiane Hanni both scored in the space of 71 seconds to snatch Spartak victory.
Arsenal's Pierre-Emerick Aubameyang shoots at goal from a free-kick.
Sporting were reduced to 10 men late on when former Barcelona centre-back Jeremy Mathieu brought down Aubameyang, but the Gabon forward blasted the resulting free-kick over the bar.
"In the last match he played 30 minutes, the best for [the BATE game] is that he plays 45 to 50 minutes".
Chelsea tops Group L with a maximum 12 points. They arrived in Belgrade in first place in the group but has ceded the initiative and will be overtaken by either Napoli or Paris Saint-Germain, who meet in Naples later Tuesday.
BATE nearly snatched a leveller in the third minute of added-on time, but Baha's 20-yard volley struck the post before Chelsea frantically cleared the ball away from danger and saw out the remaining seconds for their fourth successive win of the group.
With goals from Kieran Tierney (11th) and Odsonne Edouard (79th), the Hoops jumped to joint second in group B equal with the German club.
They got a hard group stage draw when PSG and Napoli came out of the hat with them but they continued their excellent European form with an opening round win against the Ligue 1 champions to put themselves in pole position.
In some of the other high-profile matches, Dynamo Kiev defeated Rennes 3-1, Rapid Vienna drew 0-0 with Villarreal, Real Betis drew 1-1 with AC Milan while Bayer Leverkussen beat Zurich 1-0.