Kolkata: Former champions Atletico de Kolkata (ATK) edged past ten-man Mumbai City FC 3-2 in a rip-roaring semi-final first leg of the Indian Super League at the Rabindra Sarovar Stadium here on Saturday.

This was ATK's second home win this season.

ATK took the lead in the third minute through Lalrindika Ralte but soon fell behind to two goals from Mumbai's Leo Costa and Gerson Viera.

But the fate of the match swung rapidly in the hosts' favour with Iain Hume striking a brace (39th and 45+4) towards the end of the first session.

Mumbai's Diego Forlan was sent off in the 74th minute after a double booking. The 2010 World Cup Golden Ball winner was booked first in the 51st minute.

ATK play in Mumbai for the second leg next Tuesday.

To the surprise of all, Jose Molina ringed in six changes with the likes of Debjit Mazumder -- one of their key performers under the bar -- finding a place on the bench.

Mumbai, on the other hand, handed Leo Costa and Sunil Chhetri starts in place of Matias Defederico and Udanta Singh.

ATK started as the brighter side and got their reward when the match was three minutes old, albeit from fortuitous circumstances.

Borja Fernandez's cross from the right found Ralte who knew little about his looped flick which cushioned into the top right corner, making it difficult for Amrinder to gauge.

The hosts' joy was shortlived though as the visitors drew level seven minutes later.

Forlan's free kick found Chhetri, who nodded the ball in the path of Costa for the Brazilian to slot it in.

The boisterous 12,500 crowd was stunned to silence moments later when the blue shirts took the lead.

ATK's sloppy defending was for all to see as Gerson Viera banged in a Forlan inswinging free kick with Henrique Sereno caught napping.

Fernandez came close to equalising soon after the setback but his effort flew over.

He was in the thick of things again when Hume headed back for Doutie to shoot on the half volley. Thankfully, Goian was at the right place at the right time to get an important deflection for keeper Amrinder to save.

Just when it looked like Mumbai would go into the break with their noses ahead, ATK not only restored parity but went ahead for the second time in the game.

Hume scored both the goals. First Ralte crossed from the byline for Doutie to set up Hume after Amrinder only got his fingertips to the ball. Hume then smashed home as Amrinder was left stranded.

In the first half added time, Lalhmangaihsanga Ralte tripped Postiga inside the box to concede a penalty which Hume comfortably tucked in to the keeper's right.

After the breather, Hume and Chhetri were guilty of wasting two good chances.

It became an uphill task for Mumbai when their star player Forlan saw his second yellow card of the game for kicking Jewel Raja after the Uruguayan failed to win a duel with him.

Sehnaj Singh got into the referee's book soon after as Mumbai seemed to be losing their cool.

Hume came close in the dying minutes of the game, but his fizzing shot finished off-target.