Costa scores in Chelsea colours
Diego Costa scored on his Chelsea debut as the Blues came from behind to beat Slovenian outfit Olimpija Ljubljana 2-1 away in a friendly on Sunday.
After the hosts had taken the lead through Nik Kapun's 40th-minute strike, striker Costa levelled the match 10 minutes into the second half, converting a through-ball from his fellow Spain international and summer recruit Cesc Fabregas, who was also making his bow for his new club.
Eight minutes later, defender Kurt Zouma prodded in the winner, following up a Fernando Torres shot that had been parried.
Torres subsequently chested a simple opportunity over the bar from close range as he met Nathan Ake's cross.
Chelsea's Barclays Premier League rivals Everton and Leicester were also in action overseas, playing each other in Bangkok with the Foxes winning 1-0.
Foxes forward Gary Taylor-Fletcher provided the only goal of the game in the 66th minute, tapping in a centre from the right from Jamie Vardy, who had got to the ball before Toffees goalkeeper Joel Robles.
The two clubs meet again at the King Power Stadium on the opening day of the top-flight season.
Swansea put in a dominant performance as they triumphed 4-0 at Plymouth, with summer signing Gylfi Sigurdsson netting a brace.
The Premier League side were 1-0 up on nine minutes as Rory Donnelly capitalised on a mistake by Pilgrims goalkeeper Luke McCormick.
After the break, Jordi Amat doubled the advantage before Sigurdsson - back on a permanent deal at the club he previously played for on loan in 2012 - struck twice, the second being a superb curling free-kick at the death.
Later on Sunday, Manchester City claimed an impressive 5-1 victory over AC Milan in a weather-hit friendly at Heinz Field in Pittsburgh.
Stevan Jovetic handed the Premier League champions the lead after 12 minutes with a low shot that creeped in at the near post and three minutes later Gael Clichy picked out Scott Sinclair in the box and he slotted home the second from close range.
The goalfest was not over yet and midway through the first half Jesus Navas' acrobatic effort from just outside the box took a huge deflection and left goalkeeper Michael Agazzi with no chance.
Rampant City added a fourth after 27 minutes as Nigerian striker Kelechi Iheanacho, who has been training with the club for the past few weeks, picked the ball up on the edge of the box and turned 180 degrees before firing home.
Sulley Muntari pulled one back for Milan just before the break as he tapped in with a close-range finish at the home of NFL side the Pittsburgh Steelers.
Following a delay due to lightening and heavy rain, former City striker Mario Balotelli took to the field for the second half and had a goal ruled out for offside before Jovetic netted his second to make it 5-1.