Sri Lanka seamer Nuwan Pradeep is likely to miss the Test series with England starting this week because of anterior cruciate ligament damage.
The uncapped 24-year-old took 4-29 in the second innings of the tour match with the Lions last week and could have made his debut on Thursday in Cardiff.
"He has a bit more pace than the rest of them so it's a shame if he has to go home," coach Stuart Law said.
Sri Lanka have added Lancashire all-rounder Farveez Maharoof to the squad.
Asked about the extent of Pradeep's injury, Law added: "He has some damage to his anterior cruciate ligament.
"He is seeing a specialist at the moment, it's bad news for the young man.
"He's one of the cards up our sleeve. If things are OK and he doesn't need an operation we may opt to keep him here, but at this stage it looks like he's flying home."
Maharoof, 26, was not originally selected for the three-Test series but is in England as the Red Rose's overseas player for 2011.
However, he featured in Sri Lanka's as some players were still taking part in the Indian Premier League.
Paceman Dilhara Fernando is thought to be struggling with a knee problem.
He played through pain to take three wickets in each innings in Sri Lanka's at the weekend.
The tourists are already missing pace spearhead Lasith Malinga, who has .
But Maharoof, a veteran of 20 Tests and 94 one-day internationals, would be an experienced alternative to Fernando.
Sri Lanka's other seam bowlers have played only eight Tests between them - six for left-armer Chanaka Welegedara and two for Suranga Lakmal, while Thisara Perera is yet to play a Test despite featuring in limited-overs matches.
A Sri Lanka spokesman said: "Maharoof has been called up and is already with us.
"He will be cover for one or two nagging injuries which we will be assessing."
Maharoof made his Test debut in 2004 but has not featured since November 2007.
However, he has taken eight County Championship wickets at an average of 30.25 in three games for Lancashire, while also averaging 65.33 with the bat after