Sir Ian Botham is backing Sri Lanka to make things uncomfortable for England when the five-match ODI series gets underway at Trent Bridge on Tuesday, live on Sky Sports.
The tourists recorded a 3-2 win when the sides last met on English soil in 2014, and Botham expects Angelo Mathews' men to be very competitive again, despite being brushed aside in the Test series.
The Sky Sports commentator said: "It may have been comfortable for England in the Test series but this is a different format and one England have struggled with for some time.
"These guys can play one-day cricket - they have a better record than England in this format and if you write them off it will be at your peril."
England lost their last series in the 50-over format to South Africa 3-2 in the winter - having lead 2-0 - but are odds-on to secure victory this time.
Despite being without all-rounder Ben Stokes, Botham is backing England to win the series and has picked Jos Buttler to top score in the series at 7/1, one of his Sky Bet Beefy's Bets.
He added: "Joe Root is rightly the shortest price and my pick for the first match at Trent Bridge, a ground he enjoys.
"But if England get a couple of matches ahead they might rest him so I think there's better value in backing Jos Buttler at 7/1 to be the series top bat.
"He's probably going to play in all the matches and if they are going well they can move him up the order."
Botham is also backing Root's Yorkshire team-mate Adil Rashid to be England's top series wicket-taker at 4/1.
Watch England and Sri Lanka's first ODI from 1.30pm on Tuesday on Sky Sports 2. Or watch for £6.99 without a contract, on NOW TV.