( CNN ) -- Argentine midfielder Esteban Cambiasso scored the winning goal as Jose Mourinho 's Inter Milan defeated former club Chelsea 2-1 in the first leg of their Champions League last 16 tie at the San Siro . Cambiasso drilled home a low shot from 18 yards out , just four minutes after Chelsea had levelled matters , to leave the tie finely poised ahead of the second leg at Stamford Bridge in three weeks . All the talk beforehand had been about the two coaches , Mourinho and Carlo Ancelotti -- with no love lost between the pair from when Ancelotti was in charge of Inter 's rivals AC Milan , who share the San Siro with them . Added to the mix was the fact that Mourinho was still highly-thought of by many at Chelsea after leading the club to successive league titles in 2005 and 2006 . And it was Mourinho 's side who struck first , taking a third minute lead when Diego Milito cut inside John Terry before firing home a shot inside goalkeeper Petr Cech 's right-hand post . In a frantic opening 45 minutes , Didier Drogba struck the bar for Chelsea with a fierce free-kick while they also had a penalty claim for a tackle on Salomon Kalou turned down . However , Chelsea did equalize six minute after the re-start . Fine work from right-back Branislav Ivanovic saw him skip a couple of challenges before laying the ball off to Kalou , who curled home a shot fromt he edge of the area that goalkeeper Julio Cesar should have done better with . But Cambiasso quickly restored Inter 's advantage and Cesar then made up for his error on the goal by keeping out Frank Lampard 's close-range strike . Chelsea may have to do without keeper Cech for the second leg . The Czech Republic international appeared to damage his knee while rolling the ball out and had to be stretchered off . His possible absence would be a major blow for the London side as they fight for trophies on three fronts this season . Meanwhile , in the evening 's other Champions League tie , Primera Liga side Sevilla look favorites to progress after earning a 1-1 draw at CSKA Moscow . Alvaro Negredo gave the Spanish side a 25th minute lead when tapping home at the far post from a pinpoint Jesus Navas cross . But the home side levelled midway through the second half when Mark Gonzalaez , who ironically joined CSKA in the summer from Sevilla 's city rivals Real Betis , fired home an unstoppable long-range drive that gave goalkeeper Igor Akinfeev no chance .
Esteban Cambiasso scores the winner as Inter Milan defeat Chelsea 2-1 . The result leaves Champions League last 16 tie evenly poised ahead of second leg . CSKA Moscow recover to draw 1-1 with Sevilla in the evening 's other tie .