Sri Lanka Cricket's chairman of selectors, Ashantha de Mel, said that Eranga was picked as the team needed to bolster its pace attack, especially with Lasith Malinga [ Images ] uncertain.
"Lasith Malinga is nursing a groin strain and he was left out of the first match against India [ Images ]," De Mel said.
The all-rounder was originally named in Sri Lanka's Test squad to play Pakistan in the UAE last year, but had to withdraw with a shoulder injury to his right arm.
"He will most probably play in tomorrow's game against Pakistan. We thought Eranga, who has recovered from his shoulder injury, would be useful because he can bat as well," he added.
Eranga, who returned impressive figures of four for 65 in his Test debut against Australia [ Images ] at the SSC last year, has a first-class hundred and four half-centuries in 41 matches.
A calf injury had ruled out Mathews, dealing a blow to Sri Lanka's chances in the four-nation tournament.
Mathews had missed the finals of the recently-concluded Commonwealth Bank series in Australia due to the same problem.
"The last couple of days Angelo has had some fitness tests, he hasn't pulled through those well, so we made a call to send him back home," Sri Lanka captain Mahela Jayawardene [ Images ] said.
"He will try to get ready for the Test matches (against England [ Images ]) that starts in about ten days' time."
The team is yet to confirm injured pace spearhead Malinga's availability for Thursday's match against Pakistan.
"Malinga played through injury in the final two matches of the CB series, so we decided to give him a break against India.
"Yesterday he bowled a bit, he will be bowling today as well, and after his bowling session we will take a call on him tomorrow," Jayawardene said after a training session here.