Sri Lanka's batting has been brittle, and they are missing their finisher with the ball, but T20 wits, they hope, will be enough to put them into the semi-final. First up in their Delhi double-header is England - a team they have sometimes outsmarted before.

There is evidence that this England side is savvier than its predecessors. They have hired experts to advise them on spin, and are led by one of the more unorthodox England captains. But, Sri Lanka are hoping they are savvier still. Since the loss to West Indies on Sunday, Sri Lanka have spent their break training and introspecting, but also plotting, vice-captain Dinesh Chandimal said.

"We have six days' rest since the last match," he said. "Two of those days were total rest - without training. That was for players to concentrate on their own games - to watch videos of them batting well, and to analyse where they went wrong. In those days, we also made a lot of plans about how to challenge England. There will be a few small changes. Part of the reason for those changes is also to surprise them."

If Sri Lanka have something up their sleeve, there is a chance the plan involves the recently-shortened one belonging to Sachithra Senanayake. Sri Lanka's offspinners has been effective against England in limited-overs matches before, and Senanayake has been good against them in particular - in one-day cricket at least. He has taken 14 England scalps at an average of 14.57 in ODIs, and stands a strong chance of playing on Saturday, particularly with three left-handers in the England middle order.

In any case, Sri Lanka's plans are likely to feature spin, with Rangana Herath and legspinner Jeffrey Vandersay having bowled well in the tournament so far.

"Rangana can cause damage in the next two games against England and South Africa," Chandimal said. "We all know they are struggling against the spinners. We've got Vandersay, who is a surprise package, and Sachithra as well. If those bowlers do their best, we have a good chance. We all expect a lot from Rangana, but he knows how to handle those pressure situations. I think he will have a huge role in the next two games."

The spin threat may be magnified by a Feroz Shah Kotla surface that has so far played slow, though there has not been excessive turn yet. The pitch is not exactly what the Sri Lanka side encounter at home, but still presents challenges Sri Lanka may be more comfortable facing than England.

"Here, I think the pitch really helps us," Chandimal said. "England played the first two games in the Wankhede and we all know that's one of the best pitches India have got. In here, it's totally different. Wickets are slow. I think we'll have a good chance."

On the batting front, it is Sri Lanka's middle order that concerned Chandimal the most. Angelo Mathews continues to bat at No. 5, but is in much leaner form than England are used to seeing him in. The likes of Chamara Kapugedera and Milinda Siriwardana are also yet to make a major impact in the tournament.

"We're struggling with the batting - especially the middle order. It can happen when you come to big games like this. We don't have experienced guys in the middle. Guys are really working hard in practice. If our middle order clicks together, we'll have a good chance anyway.

"But, you can't say every time that it's our transition period. We've got some experienced guys, as well as youngsters. We have to put our hands up and perform for the side."

England had been the only side that defeated Sri Lanka during their run to the title in 2014, and yet, Chandimal felt this England side was better equipped than that one.

"They've got some good players, I think, especially compared to the past five or six years, when I think they weren't concerned about the T20 format. Now, they are thinking. They've got Root and Buttler - they are the key players. They are playing really well. We never underestimate any team. We'll have to play our brand of cricket."

Andrew Fidel Fernando is ESPNcricinfo's Sri Lanka correspondent. @andrewffernando