Apart from running out Joe Root (three), Mathews also took the wicket of the recalled Moeen Ali (15).
Meanwhile, opener Jonny Bairstow became Kasun Rajitha’s first wicket of the match after scoring 30 runs in 31 balls.
Captain Jos Buttler scored eight runs and returning Liam Livingstone fell victim to fast bowler Lahiru Kumara after scoring just one run.
Chris Woakes’ disappointing performance in the World Cup continued when he fell to Rajitha for a duck in the 26th over, taking England’s score to 123-7.
Woakes was dropped after the 229-run defeat to South Africa, but his comeback ended in just four balls as Sadira Samarawickrama took a low catch at point.
At the non-striker’s end, Stokes suggested that the catch was not clean, but on review the batsman was given out.
After Woakes’ departure, England’s hopes rested on Stokes, but he fell for 43 when he edged substitute fielder Dushan Hemantha off Kumara’s bowling.
Stokes scored runs in 73 balls with the help of six fours, taking England’s score to 137-8.
Adil Rashid was run out in comical fashion when wicketkeeper Kusal Mendis noticed that he had gone too far down the wicket.
Spinner Mahesh Theekshana ended the matter by stumping Mark Wood for five runs.