Mathews will sit out the five-match series against England, which gets under way in Dambulla on Wednesday, after being dropped in acrimonious circumstances by selectors.
They claimed the 31-year-old was not sufficiently fit, while head coach Chandika Hathurusingha took the curious decision of drawing attention to Mathews’ “world record” for involvement in run-outs.
Chandimal must therefore attempt to secure a first Sri Lankan win in 10 series without a player who averages a shade under 60 since the start of 2017.
Speaking on the eve of the series, Chandimal said: “We all know he is our best batsman, especially when it comes to the shorter formats.
“I hope he will identify what he needs to do to come back to the side and come back strongly. It is mainly his fitness.”
All the pre-series signs suggest Sri Lanka will do well to preserve their proud limited-overs record against the ICC’s top-ranked team.
On home soil they have won 15 of the 21 ODIs between the sides and Chandimal’s best hope of continuing in that vein appears to hinge on spinners Lakshan Sandakan and Akila Dananjaya.
“These conditions are very different to what England are used to playing in,” Chandimal said.
“The pitches here spin and it is not an easy thing to play especially for the batters. Overall comparing our boys to England, they have more experience but we have more mystery spinners in our side.
“When you are a batsman if there is a mystery spinner you have to try to go for innovative shots, then you can put the pressure back on him.”
The former Australia coach resigned from his post at the end of March following the infamous ball-tampering episode which occurred during the team’s tour of South Africa.
Captain Steve Smith and his deputy David Warner were both stripped off their posts and handed one-year bans from international cricket by Cricket Australia while Cameron Bancroft was banned for a period of nine months following the scandal.
The incident forced Cricket Australia to make drastic changes to the setup with Justin Langer subsequently appointed as the head coach while Tim Paine took on the Test captaincy reins.
Lehmann, who has been out of work ever since, is now looking to get back to coaching in some capacity by next year.
I’d like to coach again one day. I think I’m a good coach, my coaching record is pretty good,” Lehmann told Australian Associated Press at the launch of Fox Cricket.
“At some stage I’ll get there. A shorter commitment is probably the way to go … that’s probably what I’m looking for.
“But I’m just going to stay away from it this summer, watch the cricket and enjoy it. See what comes up next year.”
The 48-year-old has also backed Smith and Warne to bounce back from their bans while adding that he has maintained regular contact with them during the period.
“I speak to them (Smith and Warner) all the time. They’re going alright,” Lehmann added.
“They’ll come back really well. They’re good young men and they’ll come back. They’ve been training, hitting and they’re fit. Spending some time away from the game as well.
“I’d love them to be available for domestic cricket but that’s not my decision. That’s the powers above me.”
Under Lehmann’s tenure as Australia coach, the side won the 2015 ICC World Cup at home while also notching up home Ashes victories in 2013-14 and 2017-18.
As captain Morgan has spearheaded England’s shift from also-rans at the 2015 tournament to top of the rankings ahead of next summer’s edition on home soil, and is the country’s top scorer in one-day cricket with 5,618 runs.
Despite his considerable position of strength, the Dubliner has made it clear that nobody should consider themselves certainties over the next eight months.
Speaking on the eve of England one-day series against Sri Lanka, Morgan told Sky Sports Cricket: “When you drop yourself as captain it almost sets that example, that nobody’s place is cemented in this side.
“If I’m not supposed to be in the team I’ll be the first one to say it. If it means making a tough decision I’m more than capable of doing that.
“It’s a brave call, but we’ve come a long way with this team. We need to put ourselves in the best position in order to be contenders. If that means I’m not good enough to be in the team, both as a captain or as a player…I’m a pretty honest guy.”
Morgan attracted criticism from some, including former skipper Michael Vaughan, when he stepped aside from a Twenty20 decider against South Africa in 2017 to take a look at the likes of Liam Livingstone and Dawid Malan.
The 32-year-old, though, is clear that he must continue putting the greater good first.
“In the past I’ve dropped myself to create opportunities for guys in order to see if they can play at international level or give them an extra chance to prove themselves,” he said.
“We’re trying to build a squad of 16 or 17 guys to win the World Cup, that’s the objective. It’s not an individual trying to get runs, not an individual trying to get wickets. It’s a team collective and everyone needs to buy into it.”
Vice-captain Jos Buttler would inherit the reins in the unlikely scenario of Morgan’s form slumping dramatically enough for him to step aside.
He is an increasingly influential figure across all formats and deputised impressively when Morgan declined to tour Bangladesh on security grounds in 2016.
Buttler stepped in for Morgan again on Tuesday, but this time it was only for pre-match media duties at the Ranjiri Dambulla International Stadium.
The wicketkeeper-batsman was in strident mood, happy to shake off the underdog tag which often follows England in the sub-continent.
They have won only six of their 21 ODIs on the island, with a solitary series victory in 2007, but are well fancied this time.
Sri Lanka lie eighth in the world after a winless run of nine series and bowed out of the Asia Cup after successive defeats to Afghanistan and Bangladesh.
“We are very happy to be favourites. We’ve been doing some good stuff and like being favourites,” he said.
“We’ve been playing well. It’s been tricky in the past for England sides to come here but we are full of confidence and looking forward to the challenge, adapting our style of play and pushing the boundaries of what we are capable of in these conditions.
“There is always pressure being number one, people want to chase you. Once you get there that’s when the hard work really starts because you have a target on your back and it’s down to you to keep improving and stay there.”