Testing at Windy Hill nine days after admission Essendon skipper Jobe Watson welcomes news that ASADA's drug investigation could take months, saying the club wants it to be as thorough and exact as possible. Essendon coach James Hird walks past two ASADA drug testers during a training session at Windy Hill yesterday. IT came as no surprise that Australian Sports Anti-Doping Authority agents swooped on Essendon's training session at Windy Hill yesterday on the eve of the Bombers' opening NAB Cup games tonight at Etihad Stadium. What was surprising is that, as the The Australian understands, it was their first visit since an AFL-ASADA investigation was opened last Tuesday week after the club admitted it had grave concerns over mystery supplements given to players last year. It was not clear how many players were required to give samples yesterday. Essendon revealed it was the first time players had been subjected to ASADA testing since last month. Captain Jobe Watson told Fox Sports he hoped the tests cleared the air on the controversy. "What you want to do in this situation, is you want it to be as thorough and exact as possible," Watson said. However long it takes, it takes. But certainly the priority is for the correct findings to happen. The Bombers were met by drug testers as gates were opened for supporters to watch their final training session of the week. A rival AFL club said yesterday it was routine to be tested, sometimes on a weekly basis. ASADA agents approached individual players for tests as they left the training track. Hopefully a sterile environment was provided within the Bombers' headquarters.