These two sides have faced each other only four times in T20 internationals. When lined up player-against-player, West Indies – also undefeated – look stronger with bat, with an in-form Shai Hope, a rejuvenated Shimron Hetmyer at No. 3, and a solid finisher in Sherfaine Rutherford.

Having as many as three allrounders – with Romario Shepherd in line to return after injury – gives them the option of playing three fast bowlers and three spinners. It’s an ideal mix in Mumbai, where the quicks (35 wickets) and spinners (34) have been equally effective, averaging 26.28 and 26.25 respectively this tournament.

It’s a big game for both sides, with matches against India and South Africa to follow next. Who will get on the points table first?

It made England’s 37 for 2 in their first six overs look far more measured, when in fact it was a patchy start typified by a labored 7 off 14 from Buttler, before he was trapped lbw to Wellalage.

Sri Lanka’s decision to bowl first after winning the toss – predicated on their comprehensive take down of Australia at this venue in the Group Stages – looked vindicated, even as Salt battled humid conditions to reach his first half-century of this World Cup – and second in all T20I editions – from 36 deliveries. That Jacks’ 21 was England’s second-highest score spoke to the awkwardness of the innings.

Dasun Shanaka marshaled his attack well, helped by the consistent threat of Dilshan Madushanka (2 for 25) and Maheesh Theekshana (2 for 21). But Sri Lanka’s captain was brought back down to earth when he found himself in the middle with a ball left of the sixth over.

Having thumped two sixes on his way to 30, an attempt at a third was brilliantly relayed on the midwicket fence to leave Sri Lanka 82 for 8, with all their full-time batters now back in the hutch. Naturally, Jacks was a key figure in that dismissal, taking the catch before casually lobbing it back into play, straight to Tom Banton.

Dushan Hemantha had already trimmed his own bails with his bat in comical fashion, before Dushmantha Chameera and Madushanka, the final two batters, were both bowled slogging, in keeping with a cavalier approach when sensible heads were required. Even with the all out attack, Sri Lanka could only muster 95 in 100 legal deliveries.

You should never travel without insurance, and in Jacks England have the ideal safety blanket for a subcontinental T20 World Cup. And like insurance – in principle at least – Jacks has saved the team when they’ve least expected it.

For all the admiration for Jacks’ talents, as evidenced by his selection for the Ashes at the start of this winter, few would have predicted this emergence as a talismanic figure for England’s World Cup hopes.

You could argue the opportunities Jacks has taken should not have presented themselves in the first place. Nevertheless, the team have leaned on him against Nepal (39*), Scotland (16*) and Italy (53*), all unbeaten knocks from the defacto No.7 that pulled them out of sticky situations.

Now an established threat, he loomed in the background as England’s top order stumbled to 68 for 4 after 10 overs, before Sam Curran’s dismissal brought Jacks to the crease at 94 for 5 at the start of the 14th.

His 21 off 17 was the slowest of his four double-figure scores at this tournament, and Sri Lanka did well to cap his work, removing him with seven balls to go. Unfortunately for them, Jacks took that personally.

“He always tells me he bowls better when he’s angry,” said Brook after the match. Jacks channelled that rage into a good length from around the wicket, both to right- and left-handers. A leading edge from Mendis and a horrid hack from Rathnayake got him back-to-back rewards, before Wellalage’s gifted him a third in his final over.

That he bowled the first four from one end speaks to the amount of trust now placed on Jacks and how well he is responding to it. He now has three player-of-the-match awards at this World Cup.

Buttler said he would not curb his attacking intent in search for better form at this T20 World Cup, and he was true to his word. A length delivery from Wellalage was met with an attempted reverse sweep, Buttler upright looking to access behind point, where there was empty (patchy) green to exploit.

Unfortunately, Buttler’s bat could not have been further from the ball as it clattered into his knee, in front of middle stump. That he even had the conversation with Salt about reviewing was galling; surely he knew he was plumb? The desperation for reassurance from his opening partner was misguided, and Salt had little to offer. Buttler turned on his heels and marched off as quickly as he could.

That, arguably, was the soundest judgement he showed on Sunday. Taking a review back to the dressing room would have made the innings worse.

The four dot balls in the previous over off Madushanka were painful to watch. England’s greatest white-ball batter is clearly out of sync with his movements, even his trigger, turned inside out by the left-arm quick’s movement across him, which almost cost him his off stump.

Buttler is now averaging 12 in this World Cup. This innings – his third single-figure score in succession – is his 12th without a half-century. How far off are England from having a conversation about the former captain?

A long way given how much credit Buttler has in the bank and Brendon McCullum’s ethos of backing your headline acts to the hilt. “He’s a powerhouse of world cricket,” said Brook defiantly. “He’s arguably the greatest white-ball player to ever play the game”

But 35-year-old Buttler is struggling badly. Badly enough that his dismissal was, ultimately, a good thing for the team.

At the halfway stage, Wellalage was probably sitting back, admiring the part he had played in another Sri Lanka win. Until he was rudely jolted out of his chair by the start of a terminal top-order collapse.

The left-arm spinner found himself back out there 3.4 overs into the second innings, the pressure he had put on England now being shoved right back at him, his exceptional 3 for 26 split across three phases of the game on its way to being deemed obsolete.

Despite the result, Wellagage’s ability to knit together not just his own overs, but those of the bowlers around him, was a silver lining. And a reminder of the maturity he possesses at the age of just 23.

The injuries Sri Lanka have suffered in their bowling stocks means he has been tasked with being that much more consistent. And he did right by his captain, first showing immense control during his two powerplay overs (1 for 16) before bravery in overs 10 and 15 brought him the wickets of Brook and Salt.

With the limits of the outfield sodden after heavy overnight rains, the sponge was brought in, reducing the size of the boundaries. With an enticing hit back over his head, Wellagage was unperturbed when slowing the pace down, which allowed him to sneak one into the pad of Brook. A bit of loop then did for Salt, whose tired thump down the ground fell into the hands of Dushan Hemantha at long off.

Wellagage’s spell would have been the jumping off point for a celebration of a well-rounded attack. In the end, it is nothing more than a footnote in a catastrophic defeat that already has Sri Lanka up against it to qualify for the semi-finals.

Brief scores:
England 146 for 9 in 20 overs (Phil Salt 62, Harry Brook 14, Sam Curran 11, Will Jacks 21, Jamie Overton 10*; Dilshan Madushanka 2-25, Dunith Wellalage 3-26, Maheesh Theekshana 2-21, Dushmantha Chameera 1-34) beat Sri Lanka 95 in 16.4 overs  (Dunith Wellalage 10, Kamindu Mendis 13, Dasun Shanaka 30, Maheesh Theekshana 10*; Jofra Archer 2-20, Will Jacks 3-22, Liam Dawson 2-27, Adil Rashid 2-13, Jamie Overton 1-13 ) by 51 runs

[Cricinfo]