Eden Hazard's stoppage-time goal spared Chelsea - and Rafa Benitez - blushes, to give the Blues a 2-1 aggregate victory over Sparta Prague, and send them through to the last 16 of the Europa League.
It was a far from convincing performance by the hosts, drawing 1-1 on the night at Stamford Bridge, against a well-organised Czech side, who can feel aggrieved not to have at least taken the two-legged tie to extra-time.
Sparta striker David Lafata gave the visitors the lead, albeit against the run of play, with only 17 minutes on the clock. His close-range shot high into the net gave Petr Cech no chance in the home goal.
Chelsea had started the brightest, though, with Fernando Torres missing a good chance in the first five minutes, after some neat work on the right wing by Victor Moses. The Nigerian's cut back to the Spanish striker didn't get the finish it deserved, the shot going wide of the far post.
At the other end, Cesar Azpilicueta's stunning block denied Lafata from six yards out, before Torres missed his second of three glorious first-half chances, this time volleying Juan Mata's chipped cross to the back post, over the bar.
After Lafata's opener, Brazilian midfielder Oscar - who was arguably Chelsea's most creative player on the night - had a brief glimpse at goal. But, his half-volley was expertly cleared by Sparta defender Ondrej Svejdik.
On the half hour mark, Tomas Prikryl came close to doubling Sparta's lead. However, Cech saved well at his near post, palming the ball out for a corner.
Mata had an effort diverted over the bar by the impressive Tomas Vaclik in the visitors' goal, prior to Torres's worst miss of the night - an unchallenged header from eight-yards out - which went over the bar, moments before the break.
A crowd of 38,642 watched tonight's first ever Europa League game hosted at Stamford Bridge, including 3,000 away supporters, each wearing a red, yellow, and blue hooped wooly hat, handed out free to fans in protest, after Chelsea officials denied entry to Sparta's usual travelling banner.
After the restart, Chelsea almost equalised immediately, following a swift counter-attack that was led by Oscar. His lay-off to compatriot Ramires, saw the South American cannon a shot off the post.
Moses hit a speculative 20-yard effort, and moments later, Torres went through again, only to be denied by the outrushing Vaclik, to retain Sparta's precious lead.
John Terry went close on the hour mark, flicking on Torres's forward header, before Hazard replaced Oscar, much to the distaste of Chelsea supporters, who aired their dissatisfaction at interim manager, Benitez.
Vaclav Kadlec missed a rare second-half opportunity for Sparta, after Gary Cahill recovered well to deny the forward, then Tomas Zapotocny unleashed a fierce shot over the bar from the edge of the Chelsea box.
Ramires skewed another decent chance wide after an intricate piece of one-touch football, that involved Mata and Moses. And, Leony Kweuke made a late cameo for Sparta, replacing goalscorer Lafata, who came off to a standing ovation.
Then, with the last kick of two minutes stoppage tiime, just when it looked as if the game was heading to extra time, substitute Hazard came to the rescue for Chelsea, after his left-footed shot beat Vaclik at his near post, to send the Blues supporters home satisfied, if not entirely happy.
Chelsea: Cech; Azpilicueta, Cahill, Terry (c), Bertrand; Mikel, Ramires; Moses, Mata, Oscar (Hazard 69); Torres.
Subs not used: Turnbull, Cole, Luiz, Ferreira, Marin, Benayoun.
Sparta Prague: Vaclik; Zapotocny, Holek, Svejdik, Hybs; Prikryl, Krejci, Matejovsky, Vacha, Kadlec (Bednar 90+3); Lafata (Kweuke 82).
Subs not used: M.Cech, Pamic, Vidlicka, Polom, Janos.
Venue: Stamford Bridge
Referee: Aleksandar Stavrev (Macedonia)