Pakistan off-spinner Saeed Ajmal has been reported to the International Cricket Council (ICC) over a suspected illegal bowling action.
The 36-year-old raised concerns of match officials during the seven-wicket first Test defeat by Sri Lanka.
He is required to undergo testing within 21 days and is permitted to bowl in international cricket until the results are known.
Ajmal has taken 174 wickets in 34 Tests at an average of 27.79.
He is the leading wicket-taker in the County Championship this summer, having taken 63 wickets in nine matches for Worcestershire before joining up with Pakistan last month.
In February 2012, the Pakistan Cricket Board was forced to clarify Ajmal's claims that he had been given special dispensation to straighten his arm 23.5 degrees in his bowling action - more than the ICC's 15-degree limit.
After he took 24 wickets as Pakistan whitewashed England 3-0 in a Test series in Dubai and Abu Dhabi, Ajmal said he was allowed more leeway because an accident left his arm with a resting position of an 8.5-degree bend.
At the time, then-ICC general manager Dave Richardson, now the chief executive, said that Ajmal's action had "not been cleared for life".
The second Test between Pakistan and Sri Lanka in Colombo begins on Thursday.