Once again the uncertain nature of the T20 format came to the fore when Mumbai Indians were defeated by a big margin by the Chennai Super Kings in the IPL eliminator on Wednesday evening. The Chennai team had lost both their earlier encounters to Mumbai but, when it came to the game that mattered, they raised the level of their game and beat the much-fancied Mumbai outfit. They will now take on the team that finished top of the points table, Delhi Daredevils, for the right to play the Kolkata Knight Rriders in the final on Sunday. In the T20 format, chances are to be taken and many a gamble has come up trumps for a team, but there has also to be a cricketing thinking behind such gambles. That thinking has not been seen with most teams this season, and so some moves have flopped miserably. There is little room for tactics in the game since it is a slam-bang format, but it is here that a good captain will use his bowling resources well. He will know when to bring his best bowlers on and when to risk another over from a lesser bowler. Gautam Gambhir has got this right more times than others and that is why his team, KKR, are in the final on Sunday. Delhi captain Virender Sehwag, on the other hand, missed a trick or two. To give the last over of the Kolkata innings to Varun Aaron, who has just come back from injury, was an unnecessary risk and it didn\'t work as Aaron was taken for 21 runs. Captains usually have their best bowler bowling the last over of the innings when they are fielding first, and the penultimate over of the innings when they are defending a total. The idea is quite simple: if the opposition have wickets in hand, they will go hell for leather in the final overs, and it is here that the best bowler will be able to stop them.While defending, if there are 20 runs needed, then it will be better for the best bowler to bowl the penultimate over and give away say six runs, and that will make it easier for the lesser bowler to defend 14 runs. On the other hand, a lesser bowler may concede 16 runs in the penultimate over and that leaves no pressure on the batsmen to get the runs needed off the best bowler in the team. Sehwag also went in with four seam bowlers on a pitch where it is easier to use the extra pace to score off than against if you\'re facing.