An away goal scored by Salomon Kalou leaves the tie on a knife edge after a night when Chelsea can feel aggrieved over another Champions League penalty decision and lost Petr Cech to injury.

The strike from the Ivorian, who enjoyed one of his most influential games of the season, came shortly after half-time and was sandwiched between two strikers from Inter's Argentines - Diego Milito and Estaban Cambiasso.

The first came early in the game and had much to do with slack Chelsea defensive play, the only real black spot on an otherwise competent performance in a difficult away fixture.

Just before half-time came the game's major talking point when Kalou should have been awarded a penalty. That Walter Samuel fouled the Chelsea man yards inside the box is indisputable.

Now we await news of Cech, who was carried away on a stretcher having suffered injury with no-one near shortly after Inter's 54^th minute winner.

When it came to standing in for the two left backs injured before this game, it was Malouda rather than Belletti who was asked to play left-back, the France international resuming a position he had played at times in his Lyon days.

The remainder of the side pretty much picked itself based on this season's form and current availability. Ancelotti's main decisions were Carvalho over Alex and Kalou rather than Joe Cole as the other support attacker behind Drogba.

The Drogba v Lucio contest started the very first time Chelsea crossed the halfway line, our striker left prone over the touchline after a chopping tackle by the Brazilian. The referee allowed no treatment.

The match continued and inside three minutes the home side took the lead. Eto'o had possession just outside the area and his pass forward towards Sneijder could have been cut out but instead found its way to Milito who had run behind Ivanovic.

The Italian side's top scorer then sidestepped Terry and beat Cech just inside the near post. The San Siro roar was as long as it was loud. Chelsea had not been tight enough at the back and now faced a stern test.

On eight minutes Motta went into the book for a high boot that racked Ballack's cheek and the German floored and in pain.

Kalou, on the left, had a job to do in giving Inter right-back Maicon enough concern to prevent his runs forward at Malouda, made space for himself and had Chelsea's first shot on target but it was straight at Cesar.

That was on 12 minutes and two minutes later Drogba came within an inch or two of slamming Chelsea back level from 35 yards. His free-kick, won for a foul on Ballack had Inter's Brazilian keeper floundering as it smashed against the crossbar, bouncing down and out. White Chelsea shirts challenged, the ball came back to Drogba but his follow up shot was time caught by Cesar.

Ancelotti's men were working Mourinho's keeper. From 25 yards Ballack made him save low down on 18 minutes.

On 22 minutes there was a worrying moment when Ivanovic's surge up the right was halted by Motta and Milito was able to attack Carvalho in the box. The Argentine couldn't manage it without a clear dive and was rightly booked. Less certain was the challenge by Kalou on Sneijder that earned him a yellow seconds later. Low and seeming to get the ball, it could only be because the ref spotted danger in the slide.

Drogba was not too far away from pulling off a difficult, falling volley before Mikel joined the list of players who had shot straight at Cesar from outside the box.

There was a huge escape by Chelsea when Eto'o miss-kicked just six yards from goal on 33 minutes. The derision from the home fans was not too far short of the noise for the goal. Inter had been quick to counter when Kalou had lost possession in his own half and it was Sneijder's cross that had cut Chelsea open.

That was from our right side, the area of most Inter pressure throughout the first half. Malouda on the opposite flank had so far had an easy ride defensively although did let Maicon escape him for one attack.

Kalou almost inadvertently headed Drogba's rocket of a cross towards goal but it looped off target.

Then in stoppage time at the end of the half, Inter were caught napping and Kalou, who had seen as much of the ball as anyone, had a run on goal, only to clearly have his legs taken from behind by Samuel on the edge of the six-yard box.

Spaniard Manuel Mejuto Gonzalez waited and then waved play on. Chelsea were incensed. Oh those Uefa referees!

So it was still 1-0 at the end of a half more open than might have been predicted on a pitch good by the San Siro's notorious standards. Chelsea had enjoyed more possession and more time on the attack.

Given the injustice just before the break, how sweet was Kalou's equaliser just five minutes after it? He swept the ball into the bottom corner from the edge of the area with a wonderful strike. Ivanovic, in the build-up had shown bags of personality, bullishly charging into space before slipping the ball infield.

We were level on goals but had an away strike to our name, however the Chelsea supporters' joy high in the top tier of the Curva Norda lasted a mere four minutes. A clearing header by Carvalho was struck well on the volley by Cambiasso, straight into the body of Ivanovic. When it bounced back, the same midfielder struck it even more sweetly. There was little Cech could have done.

Four minutes later the Chelsea keeper was involved in a major incident. Having gathered a ball, he went to bowl it out but his leg buckled under him and that was his match over, wheeled away to the dressing room in pain.

Chelsea were not about to be cowed by the twin set-backs of goal and injury. Anelka found space and crossed low for Lampard to test Cesar

Mourinho changed his team shape to 4-2-3-1 by bringing on Balotelli and Pandev and when the latter found a way past Lampard on the left there was a brief chance for Cambiasso but Ivanovic blocked.

Sturridge was introduced by Aneclotti for the final 12 minutes. It was time for hard-running Kalou to rest.

It was all Chelsea in the closing stages, Cesar and Samuel having to stretch to deal with dangerous crosses and Drogba going close with a shot past the post.

The Cech injury apart, there was little in this game to suggest that a top-level Chelsea performance won't pull this one round in the second leg at home.

Chelsea(4-3-2-1): Cech (Hilario 60); Ivanovic, Carvalho, Terry (c), Malouda; Ballack, Mikel, Lampard; Anelka, Kalou (Sturridge 77); Drogba.
Scorer Kalou 50.
Booked Kalou 22

Inter (4-3-1-2): Cesar; Maicon, Lucio, Samuel, Zanetti (c); Stankovic (Muntari 83), Cambiasso, Motta (Balotelli 57); Sneijder; Milito, Eto'o (Pandev 67).
Scorers Milito 2, Cambiasso 54.
Booked: Motta 8, Milito 22.

See the game in full on Chelsea TV from midnight.