COLOMBO- Sri Lanka have 10 ODIs at home and seven matches in New Zealand before they play the World Cup curtain raiser on February 14. Angelo Mathews, Sri Lanka's captain, has expressed his desire to build a team and hone a World Cup strategy starting from the ODI series against Pakistan.The tournament is now only six months away, but several spots in the Sri Lanka XI are still far from settled. Tillakaratne Dilshan is still firing at the top of the order, but neither Kusal Perera nor Upul Tharanga have made much of their chances to bat alongside him. Lower down, Lahiru Thirimanne has been excellent in the top three, but far less suited to batting at no. 5 or later. Mathews provides some solidity to Sri Lanka's finishes at no. 6, but Thisara Perera, Ashan Priyanjan and Dinesh Chandimal are yet to cement their spots in the lower middle order.With Sachithra Senanayake out of the picture, at least temporarily, Sri Lanka have also made changes to their spin attack, with Suraj Randiv and Seekkuge Prasanna returning. All this will be playing on Mathews' mind, as he looks to firm up his 15 for the World Cup. "I'll try and use these 17 one-dayers to try and build up my team for the World Cup," Mathews said. "I won't be reluctant to make any changes. I won't be reluctant to experiment things in these ODIs. I'll try and keep it simple, but all in all I'll try to look at a good 15 for the World Cup. I'll try and give opportunities to the players we need to look at. But we need to play to win as well. It's going to be a tough ask, but we'll try and experiment a few things." The experiments will begin in Hambantota, where Tharanga is the frontrunner to open with Dilshan, but Thirimanne could be an option as well, having opened with great success during Sri Lanka's Asia Cup triumph this year. In the middle order, Chandimal is coming off a successful List A stretch with the A team, but he has strong competition in Priyanjan, who top scored in the tour-match against Pakistan on Wednesday, which the tourists lost. Mathews was typically tight-lipped on who would play on Saturday."Chandimal is in good form, Ashan Priyanjan is in good form, and legspinner Sekkuge Prasanna has also performed well. The idea is that when you get to this 15, everyone should be ready to play. I think whoever plays will make the best use of it, but I can't say for sure that Chandimal will play tomorrow."Randiv's exclusion from ODIs since 2011 is something of a mystery, given he averages a creditable 30.54 - which is comfortably better than Senanayake's average, for instance, even if Senanayake did more bowling in the Powerplay. A naturally attacking spinner who gets the kind of bounce that may be helpful on Antipodean tracks, Randiv has won his way back to the national fray through sustained excellence in domestic cricket."The pitch is a bit damp, so we can't make a decision on our final XI for tomorrow," Mathews said. "But Suraj has earned his place in the squad. He's performed really well when given opportunities in the side games. He's worked really hard to get here so I wish him all the best."