Gautam Gambhir has said he accidentally elbowed the bowler Shane Watson in the chest during a tense exchange on the first day of the third Test in Delhi.Gambhir, who scored an unbeaten 149 to drive India to 296 for 3 at stumps, clashed verbally with Watson during the middle session and then ran into him when trying for a second run."It wasn't deliberate, it just happened," Gambhir said. "I didn't need to get into this argument with Shane Watson because he had no option of getting