Chelsea opened the defence of its Champions League title by throwing away a commanding lead to draw 2-2 against Italian champion Juventus, while Barcelona needed two late goals from superstar Lionel Messi to win 3-2 against Spartak Moscow.
Brazilian midfielder Oscar marked his first start for Chelsea with two longrange goals, but Arturo Vidal pulled a goal back close to halftime and substitute Fabio Quagliarella equalized late on.
"We are disappointed and a little bit deflated to get in a great position to win the game and come away with only a draw," Chelsea manager Roberto di Matteo said. "We should have closed the game."
Oscar scored his first when he received a short pass from Eden Hazard and arrowed in a shot that took a looping deflection off Leonardo Bonucci and flew past goalkeeper Gianluigi Buffon.
His second goal less than two minutes later had no element of luck about it, beating Andrea Pirlo to the ball and executing a flick before curling a delightful effort into the top corner from just outside the area.
"It's great to see we have a player like him in our ranks," Di Matteo said.
Shakhtar Donetsk's comfortable 2-0 win against Danish debutant Nordsjaelland took the Ukrainian side top of Group E, with Armenian forward Henrik Mkhitaryan scoring in each half with excellent finishes.
In Group G, four-time champion Barcelona had Messi to thank as the Argentina forward took his season tally to 10 goals in seven games courtesy of a devastating 10-minute spell.
"To talk about Messi is to talk about excellence in football," Spartak coach Unai Emery said. "It is very tough to stop him."
Cristian Tello opened the scoring for Barca in the 14th minute, before Dani Alves' own goal in the 29th and Romulo's strike in the 59th gave the visitors an unexpected advantage.
