Chelsea in pole position after Galatasaray draw
Galatasaray's Ivorian forward Didier Drogba (L) kicks the ball in front of Chelsea's British defender John Terry (R) on February 26, 2014 at the TT Arena Stadium in Istanbul - by Ozan Kose
The visitors led at half-time thanks to an early goal from Fernando Torres, but Galatasaray improved in the second half and restored parity after the hour mark when Cameroon defender Aurelien Chedjou found the net.
A draw was a fair reflection of the way the game went, but Chelsea will now hope to finish the job in the return at Stamford Bridge on March 18.
"This is Turkish football, it's very emotional. Galatasaray are a big club with big players and it was not easy," Chelsea manager Jose Mourinho told UK Sky television.
"The first half we had chances to kill the game, (but) it's better to be 1-1 than 0-0."
Meanwhile, his opposite number Roberto Mancini admitted his team's second half display also gives them a chance.
"We played very well and I'm confident after the second half," he said.
"After this game we have a 40 percent chance to go through."
Mourinho opted to select Torres in attack ahead of Samuel Eto'o in one of three changes to the team that beat Everton at the weekend, with Ramires and Andre Schuerrle also coming in.
It proved to be an excellent decision as it was Torres who finished off a clinical breakaway to put the Blues in front with just nine minutes played, giving Chelsea the lead they deserved as their hosts paid for a poor start.
Former Arsenal man Emmanuel Eboue lost possession high up the field, and Chelsea pounced down the left flank, Schuerrle releasing Cesar Azpilicueta, who advanced into the box and drew goalkeeper Fernando Muslera before squaring for his fellow Spaniard to apply an easy finish.
It was a sixth goal in his last five Champions League starts for Torres, and it briefly silenced the boisterous Turkish fans inside the impressive Turk Telecom Arena.
Chelsea could possibly have put the tie to bed in the minutes that followed, with Galatasaray utterly disorganised and poor in possession.
Willian had an effort comfortably stopped by the Uruguayan Muslera before Schuerrle's low ball from the right - with the home defence at sixes and sevens - was met first time by Ramires at the edge of the box, but his shot flew high over the bar.
- Mancini makes tactical switch -
There was little by means of a response from Mancini's men, with Didier Drogba unable to wriggle free from the marking of John Terry and Wesley Sneijder incapable of influencing proceedings from the left flank.
Winger Izet Hajrovic saw his snap-shot from 20 yards saved by Petr Cech, but the recent signing from Swiss side Grasshoppers was then the victim of a tactical switch by Mancini, who sent on central midfielder Yekta Kurtulus in his place and changed to a 4-2-3-1 formation.
Gala improved after that and an Alex Telles cross-cum-shot had Petr Cech panicked before Burak Yilmaz put the ball in the net after a quickly-taken throw, but with an extra ball on the pitch at the time, the Spanish referee disallowed the goal, and booked Chelsea skipper John Terry for throwing one ball away.
A lively Torres almost made it 2-0 for Chelsea in the 52nd minute, bursting through the middle of the home back line before seeing his shot turned behind for a corner by Muslera.
However, Galatasaray finally started to grow into the contest in the second half, the raucous crowd receiving a lift when Gary Cahill nearly turned the ball into his own net after intercepting a Burak Yilmaz pass intended for Drogba.
The Ivorian striker almost created an equaliser against his old club in the 62nd minute, heading down a left-wing cross for Selcuk Inan, but the home captain somehow contrived to stab the ball against the post from a yard out.
The Turkish champions were not to be denied a leveller three minutes later, though, Chedjou wriggling free of his marker to convert a Sneijder corner from point-blank range.