For both these teams, ODIs are perhaps their weakest format. Neither gave themselves a great chance of making the semi-finals in last year's World Cup, and both have poor bilateral form, winning only two of their 10 previous series. As Sri Lanka move to the dead rubber at Pallekele after winning the series in Hambantota, however, they may feel they are the more resurgent outfit.
The second ODI was almost the perfect game - one of their openers hit a hundred, and a middle-order man joined him for a record-breaking partnership that came at better than a run-a-ball. Both those batsmen are relatively young - 25 and 21. Then the spinners did what Sri Lanka's coaches hoped they would - take wickets through the middle overs, after the seamers had produced an opening earlier on.
West Indies, meanwhile, had an outing captain Kieron Pollard later described as "pretty, pretty poor". Although their quicks have at times seemed penetrative through the course of the series, both bowling efforts so far have been plagued with indiscpline. At Sooriyawewa, West Indies bowled 10 wides and two no-balls. At the SSC a few days before that, they had delivered 14 wides and one no ball. Beyond just the extra runs and deliveries, these stats are indications that even when West Indies are not conceding extras, their bowlers may not have quite found their lines. In the second ODI especially, there were easy runs into the legside for almost the entirety of Sri Lanka's innings.
Pallekele, though, generally offers the most seam-friendly ODI surface in the country. Perhaps West Indies' phalanx of fast bowlers will be more effective there. But that's only if they put enough balls in testing areas.
West Indies LLWWW (completed matches, most recent first)
Sri Lanka WWLLW
In the spotlight
Wanindu Hasaranga had a good finish to 2019, but he has been outstanding across disciplines in the first two ODIs of 2020. Having won the match with the bat on Sunday, he was lethal with his googly on Wednesday, taking 3 for 30. Having hunted so long for a reliably penetrative middle-overs spinner, Sri Lanka finally have a long-term prospect on their hands. Unlike spin-prospects that came before him, Hasaranga should have no issues with his action.
West Indies' spin options, meanwhile, have been less impressive. On the same track that Sri Lanka's spinners would later go on to get six wickets, neither left-arm spinner Fabian Allen nor offspinner Roston Chase could get a wicket. That they only bowled six overs apiece is also a reflection of the fact that Sri Lanka's batsmen looked utterly comfortable against them. Before the series, Pollard expressed confidence in a light-on-spin strategy, suggesting that Sri Lanka are good players of spin, so it may be better not to feed their strength. Sri Lanka, though, have actually not covered themselves in glory against slow bowling over the last few years.
West Indies may be tempted to bring back legspinner Hayden Walsh Jr, who at least took wickets at the SSC, although he was expensive.
West Indies(possible): 1 Sunil Ambris, 2 Shai Hope (wk), 3 Darren Bravo, 4 Roston Chase, 5 Nicholas Pooran, 6 Kieron Pollard (capt.), 7 Jason Holder, 8 Keemo Paul, 9 Hayden Walsh Jr., 10 Alzarri Joseph, 11 Sheldon Cottrell
Sri Lanka will toy with the idea of bringing Dasun Shanaka in for a match. If the pitch looks like they won't need an extra spin option, they may leave out Dhananjaya de Silva to make room. Lahiru Kumara could come in for Nuwan Pradeep as well.
Sri Lanka (possible): 1 Dimuth Karunaratne (capt.), 2 Avishka Fernando, 3 Kusal Perera, 4 Kusal Mendis, 5 Angelo Mathews, 6 Dhananjaya de Silva/Dasun Shanaka, 7 Thisara Perera, 8 Wanindu Hasaranga, 9 Isuru Udana, 10 Lakshan Sandakan, 11 Nuwan Pradeep/Lahiru Kumara
Pitch and conditions
There can be seam movement with the new ball in Pallekele, particularly under lights. It is not expected to rain on Sunday, but you never can tell for sure at this venue.
Stats and trivia West Indies have lost each of their last eight ODIs in Sri Lanka. The last time they won a match here was back in 2005, when Shivnarine Chanderpaul was captain. Kieron Pollard has been especially modest on the island. After six innings, he's scored just 17 runs an an average of 2.83. He's never taken a wicket in Sri Lanka either. Avishka Fernando and Shai Hope - both openers - have each hit a hundred and a fifty in the series.
"Within the next 18 months or so, we need to be among the best four teams in all formats. That's vision of every member of the team."
Lakshan Sandkan outlines Sri Lnaka's long-term vision.
Andrew Fidel Fernando is ESPNcricinfo's Sri Lanka correspondent. @afidelf