Poor selection has destroyed the triumph. This is not the team that we expected. After losing two wickets during the first phase, it's okay. But during the middle phase(11-40) Sri Lanka have lost 6 wickets. Jeez, that is too much. Sri Lanka gotta focus, especially the middle phase. Middle phases gotta deal with ones, twos and threes. If there is any loose bowling the batsmen can whack those into the boundaries.
Furthermore, Sandakan is an unstable player. Most of us doesn't know why he has been put into the best eleven by the Sri Lankan selectors. Well, it is the time to rethink again... Next match Kamindu Mendis gotta replace Sandakan. Kamindu Mendis has the ability to bowl with two hands plus he is a good batter too...
Accordingly, Sri Lanka can strengthen their batting lineup by adding an all-rounder. So, 5 specialist batsmen, 3 all-rounders and 3 specialist bowlers. This will assist to balance the team.
Moreover, if a batting first team can get runs between 80 to 100 runs just losing a wicket during the first phase. During the middle phase maximum of losing two wickets while maintaining a run rate of 6 runs per over and during the death overs can maintain a run rate of over 10 while keeping the wickets in hand. So, a score over 350 can set as the target. Still anything over 300 is a strong target. If Sri Lanka can protect the wickets during the middle overs it will help to move for the big totals, especially in the big contests.
Finally, Sri Lanka have done a lot of mistakes in ground fielding. So, these things gotta be adjusted pretty quickly before the second ODI. It's a must to win the second ODI for the Sri Lankans to keep any hopes for a series win.