Melbourne - David Nalbandian has been fined $8,000 for unsportsmanlike conduct at the Australian Open.
The 30-year-old Argentine player was penalized for an unspecified off-court incident following his five-set, second-round loss to American John Isner on Wednesday.
Tournament officials declined to give details on Friday of the incident which led to the fine.
Nalbandian had been upset when umpire Kader Nouni's declined his request to challenge a line call because he had taken too long. The incident occurred with Isner facing break point at 8-8 in the deciding set.
Former No 3-ranked Nalbandian said afterward it was "ridiculous playing this kind of tournament with this kind of umpires."