Buttler's 101 not out off 67 balls proved to be the difference as England posted 163 for 4 after being put in to bat and then bowled Sri Lanka out for 137 in 19 overs.
England opener Jos Buttler said it was tough to get going initially before completing his maiden international century in the shortest format as he set up his side's 26-run win over Sri Lanka in the T20 World Cup match at Sharjah on Monday night. (More Cricket News)
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Buttler's 101 not out off 67 balls proved to be the difference as England posted 163 for 4 after being put into bat and then bowled Sri Lanka out for 137 in 19 overs to register their fourth win on the trot and virtually seal a semifinal spot.
"I think staying patient and keeping my head. I found it really tough early on. I managed to get a really good partnership going with Morgs (Eoin Morgan) and we tried to attack the back end," Buttler said at the post-match presentation.
"We were just trying to get something going, were finding the spin bowlers a bit tricky and thought 120 might be a good score. We each tried to take the small side and target that and I really enjoyed batting with Morgs."
Buttler took 45 balls to reach his half-century and then needed just 22 deliveries for the remaining 50 runs.
"I just use the same (bat) all the time. Even in the nets, if I find one I like, I keep it," he said about his bat.
Asked about the final ball six which took him to his maiden T20I ton, Buttler said, "I was trying to guess where he was going to bowl, to be honest. I was pretty calm. But I think at that stage I'd batted for a long time, just staying patient and hoping he (the bowler) will miss."
Buttler also effected the run-out of Sri Lanka captain Dasun Shanaka with a direct throw in the 18th over of the islanders' run chase, and he described it as a "favourite" moment.
"(The run out) was probably the favourite bit of my day. We were under pressure there for a long part of that chase knowing that (Moeen Ali) had to bowl that (missing over after Tymal Mills left injured), so to take that wicket there was crucial and I was delighted with that."
England captain Morgan said he was incredibly proud of his players for the win.
"I felt the guys had to fight unbelievably hard, particularly with the ball and in the first 10 overs with the bat. Conditions continued to change and then Tymal going down asked another question of ourselves," he said.
"But I thought Liam Livingstone and Moeen Ali stepped up unbelievably well to support the other guys with the ball. I can't fault our guys tonight. We thought it was challenging for the top of the order.
"I thought our all-round fielding performance was pretty good, given the conditions and how wet things got. We're just delighted with the win."
He said Buttler played one of his best-ever innings in England shirt.
"It was incredible to be at the other end and watch just the ebb and flow, and then just the sheer domination at the end. He really is one of the best in the game, a privilege to play with and great to have in our team.
"A combination of unbelievable skill level and the calm nature in which he goes about it. He combines them along with reading the game, knowing where and when to score. If he gets on top, he punishes you."
Morgan said Sri Lanka have pushed England more than any other team in the tournament so far.
"They've boxed above their weight so far in the World Cup so they should be incredibly proud so far of what they've achieved but we're delighted with four wins."
Sri Lanka captain Dasun Shanaka said in the whole tournament his bowlers have been outstanding in the first 10 overs.
"It's been a concern for us the back end every game. For most of the guys, it's their first World Cup and the experience is very low. When they gain more experience, they will do good for the team.
"In the second half, we knew the dew factor will be a big factor but losing wickets at regular intervals really cost the match for us. But credit to Jos and Morgan, the way they played they showed the experience behind them in international cricket," he said.
"Six months back, we were not the same team. But these boys have come a long way in this tournament and I am really happy about the way the boys have been fighting."