Updated

By Greg Stutchbury

MELBOURNE (Reuters) - Andy Roddick continued his clashes with officialdom at the Australian Open Wednesday when he questioned an umpiring decision on match point in his victory over Brazil's Thomaz Bellucci.

The seventh seed had also collided with a line umpire in his first round match, which forced him to tumble to the ground and provoked concerns he could have re-injured his knee, an injury that kept him out of the season-ending Tour Finals last year.

Roddick admonished the line judge at the time and was still annoyed at his post-match news conference Monday.

Wednesday, Roddick held match point at 40-15 when a ball from Bellucci was adjudged to be in after review by the Hawk-Eye replay system.

The big-serving American then produced what he thought was an ace to seal the victory, only for Bellucci to challenge the call.

Hawk-Eye determined the ball to be 'out', forcing Roddick to make a second serve.

However, Bellucci belted a forehand long in the subsequent rally to finally hand Roddick the 6-3 6-4 6-4 win.

Roddick then argued with chair umpire Fergus Murphy afterwards, with the American claiming he could have played the ball on his first match point.

"There was just a disagreement about a rule I guess on a continuation of a call," Roddick told reporters. "To be fair, I didn't come in here (to the media conference) till I watched the video of it.

"I was more wrong than I thought I was out on court. That being said, it was very close.

"To take away a match point at that juncture in a match, it's a big call."

HEARD SWEARING

Roddick, who was heard to swear twice in his argument with Murphy, said after watching the video the decision was not as clear-cut as he thought it had been on court.

"I guess their whole argument was whether the call came after I had already let the ball pass. It's hazy as far as either way.

"I thought I was going to be 100 percent right. It's definitely closer than I felt it was while I was on court."

Despite the bizarre ending to his match, Roddick said he was still a fan of the Hawk-Eye system.

"Hawk-Eye, overall, I feel like is probably fair.

"I have faith in it being consistent enough to where it's the same for both players.

"So, you know, if we're talking is it exact down like to if it's a millimeter off, at least it's a millimeter off for both players and no one's really getting screwed, or if we're getting screwed, we're getting screwed the same amount."

(Editing by Patrick Johnston)