Sri Lanka batsman Tillakaratne Dilshan created history on Thursday when he became the first player to successfully appeal against an umpiring decision.
Dilshan was given out by Mark Benson, adjudged caught behind off a Zaheer Khan delivery on the second day of the first Test against India in Colombo.
But he made a 'T' signal with his hands to challenge and third umpire Rudi Koertzen ruled he was not out.
Earlier, India's Anil Kumble became the first man to challenge a decision.
The Indian skipper asked for a television review by the third umpire after appeals for a Malinda Warnapura lbw off the bowling of Harbhajan Singh were turned down.
But their appeal proved fruitless when Koertzen agreed that the ball would be missing leg stump.
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The number of appeals remains intact if a challenge is upheld.
During the three-Test series only the batsman on the receiving end of the umpire's original decision or the captain of the fielding side can appeal by making a "T" sign with both forearms at shoulder height.
The International Cricket Council chose to test the procedure in Sri Lanka after failing to get consent to try out the system during England's Test series against South Africa.
South Africa's players were happy to experiment, but England's were not - and ironically lost a potentially crucial wicket on the first morning of the Headingley Test (Alastair Cook) who would have survived had the decision been referred.
The ruling body plans to review the process at the end of the Sri Lanka v India series. A similar trial was used in the 2007 Friends Provident Trophy in England, but did not receive widespread support from the players.
The use of the third umpire in international matches has previously been governed by the proviso that it is the on-field umpires alone who decide whether a decision needs to be passed onto the replay official - and then only to assist with line decisions and on whether a catch has been taken cleanly.
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