Oscar netted within 33 seconds of coming on as a substitute to ensure Chelsea FC claimed a 1-0 victory at AC Sparta Praha in their UEFA Europa League round of 32 first leg.
Despite a promising start, the reigning European champions struggled to break down a compact Sparta back line and were matched for long periods until the Brazilian playmaker's sixth goal in Europe this season ended home hopes of a draw.
As the first club to drop out of the UEFA Champions League group stage as holders, Chelsea began like a side with a point to prove. Frank Lampard was the first to test Tomáš Vaclík in the Sparta goal and Eden Hazard fired another effort across goal inside the first ten minutes, but the Czech team weathered the storm.
Sparta twice went close themselves as they grew in confidence, with new signing David Lafata stretching to direct Tomáš Zápotočný's cross over the bar and Ladislav Krejčí's deflected strike almost wrong-footing Petr Čech.
Having allowed their hosts into the contest, Chelsea were unable to dictate like they had done in the opening exchanges. Fernando Torres's 35th-minute poke brought a fine save from Vaclík after Juan Mata unselfishly laid across, but it was the last clear-cut chance the Blues would have until deep into the second half.
Indeed, for a long time it looked as though the long-range Matěj Hybš strike that stung the palms of Čech would be the closest either side would come to breaking the deadlock. However, Sparta's resilience evaporated eight minutes from time. Oscar had been on the field just 33 seconds when he exchanged passes with Hazard before tucking in neatly at the near post to make it advantage Chelsea ahead of next week's second leg.