Sri Lanka v England, 6th ODI, Pallekele December 12, 2014

'Opening spots are still open' - Mathews

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'I'm disappointed with the spinners' - Mathews

Kusal Perera and Ajantha Mendis have been dropped for the final two one-day internationals against England. Dimuth Karunaratne, the Test match left-handed opener with just six ODI caps, has been added to the squad.

With Sri Lanka having been expected to wrap up the series handily, Angelo Mathews and the selectors had hoped to don their white coats and put World Cup hopefuls under the microscope in low-pressure matches towards the back end of the tour. But now changes have been made with the series still alive and the fact the hosts could not win on the driest track of the series so far as raised a few alarms

Mathews has so far been a conservative scientist. "We don't need to panic," has been his motto of the tour. Aside from a drop here, and a tweak there, Sri Lanka' selectorial petrie dish has not seen a lot of change.

Still, there are questions that need answering before Sri Lanka ship out for the World Cup. The opening position, where Kusal has averaged less than 20 in the series so far, is the most pressing question - his replacement, Karunaratne, last played an ODI in December 2013 - but Mathews said there was also concern among the bowlers. Sri Lanka have two more ODIs in the series before they leave for New Zealand where they play two Tests and seven ODIs.

"The opening options are open," Mathews said. "The option of Mahela Jayawardene opening option is still there. We've given opportunities to Kusal. He's fared pretty well, I thought, in a couple of games. He could have done better. We expect a lot from him because he is a good player. We've got nine more games to try and experiment with the opening slot.

"The opening spots are still open. With the middle order, we are set. It's just that the spinners and fast bowlers we need to look at. Suranga Lakmal is in the squad, so he'll probably get a game. We'll see how it goes in the next game and see if we can do some experimenting in the last game."

Dhammika Prasad may make way for Lakmal in the upcoming matches, but Sri Lanka also have an uncapped wild card in their spin ranks in the form of chinaman bowler Lakshan Sandakan. Mathews backed his spinners to bounce back from a poor outing in the fifth ODI, as he likened Sandakan to the mystery spin of Ajantha Mendis.

"Lakshan Sandakan adds a bit of variety to our squad, and there's a chance we will play him - we haven't fully picked our squad for the last two ODIs though. Even if they were flat in the last match, we still bank on our spinners.

"We've played pretty good cricket in the past four games and we don't need to panic. We are batting well at the moment. The spinners have done pretty well apart from this game. We just need to get our attitude and approach right."

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