Sri Lanka have been spotless in their run to the semi-finals, coming through a tough group and staying undefeated in five games. For West Indies, on the other hand, it's been an up-and-down tournament, but they've done enough to suggest they can be a force when they get it together. Cricinfo stacks up their numbers in the tournament so far.
The overall numbers
Sri Lanka have easily been the better bowling team, but West Indies have shown plenty of firepower with the bat: their run rate of 9.05 is easily the best in the tournament, well ahead of Australia's 8.20. Chris Gayle hasn't fired consistently, but West Indies have found batting heroes in Dwayne Bravo and the exciting Lendl Simmons, who have ensured that even Ramnaresh Sarwan and Shivnarine Chanderpaul haven't had a whole lot to do in the tournament, except in the game against England.
Sri Lanka, on the other hand, have been outstanding with the ball, taking 40 wickets - only South Africa and Pakistan have taken more - at an average of less than 18 each. The batting has been pretty solid too: the run-rate of 8.12 is third among all teams.
The Powerplay overs
Both teams have been outstanding at the start of their batting innings, scoring at more than nine runs per over during the Powerplays. Sri Lanka have also done this without losing too many wickets - they've only lost five in five games, at an excellent average of 54.40.
With the ball the stats are very similar - eights wickets for each team, and an economy rate of around eight runs per over.
Tillakaratne Dilshan's outstanding form has been the main reason for Sri Lanka's superb starts. Till the end of the Super Eights, he was the only player to score more than 200 runs, of which 53% have come in the Powerplay overs. He has only been dismissed once during this period, which gives him an exceptional Powerplay average of 117 at a strike rate of more than nine runs per over. Thanks to him, Sri Lanka have lacked nothing at the start of their innings despite Sanath Jayasuriya's relatively modest form.
Andre Fletcher has been a huge disappointment for West Indies, but Simmons has been a star, scoring 62 off 43 balls.
The middle overs - 7 to 14
The difference between the two teams during this part of the innings is huge: West Indies have been exceptional with the bat but poor with the ball, while Sri Lanka have been average with the bat and superb with the ball.
No team other than West Indies has managed to either average more than 40 or score at more than eight an over between the seventh and 14th overs (though these numbers are slightly skewed by the fact that West Indies batted nine overs against England). West Indies have done both, which indicates how strong their batting has been during this period.
Sri Lanka's batting performance has been modest, but with the ball they have been awesome, taking 12 wickets - twice the number taken by West Indies - and conceding only a run a ball during the middle overs.
The table below explains why Sri Lanka have been so formidable in the middle overs, and the kind of challenges West Indies will have to overcome if they are to maintain their record during this period. Ajantha Mendis has taken five wickets in seven overs, while Muttiah Muralitharan has given little away even though he hasn't taken as many wickets. In comparison, West Indies' middle-overs bowlers have been quite ineffective.
The last six overs
Sri Lanka's lack of firepower towards the end of their innings is perhaps their only area of weakness, and the numbers indicate that West Indies have a distinct advantage here - they score at more than 10 per over in the last six, compared to Sri Lanka's 8.48.
However, Sri Lanka's bowlers clearly have the edge over their West Indian counterparts during this period, taking more wickets and going at fewer runs per over. This suggests it'll again be a clash between West Indies' explosive batting prowess and Sri Lanka's varied and canny bowling attack.
Lasith Malinga leads the way with the ball in the slog overs, averaging less than eight balls per wicket. Bravo has been among the wickets too, but he has been far more expensive, conceding nearly ten runs per over. Mendis and Murali, on the other, have managed to keep the runs in check even during the last six overs.
How the runs have been scored
West Indies have clearly been the more powerful batting team, playing fewer dot balls, running more singles, twos and threes, and striking more boundaries. What remains to be seen, though, is whether they can repeat these impressive numbers against one of the best bowling line-ups of the tournament.
The extras factor
There's little to choose between the two teams here: West Indies have bowled three no-balls and 20 wides, to Sri Lanka's two no-balls and 21 wides.