MELBOURNE: Andy Roddick admitted he was wrong in his clash with the chair umpire over his ruling on a match point after he marched into the third round at the Australian Open on Wednesday.

The straight-shooting American finished his 6-3, 6-4, 6-4 win over Brazilian Thomaz Bellucci by arguing with umpire Fergus Murphy over a Hawk Eye video review decision which went against him on the first of his two match points.

The video review ruled that a Bellucci volley had fractionally clipped the line saving the first match point, but Roddick contended that he wasn't allowed to play the shot by an out-call from a line judge.

Even when he won the next point to clinch victory, the seventh seed continued haranguing the umpire as he walked to the net to shake hands with the 35th-ranked Bellucci.

"There was just a disagreement about a rule on a continuation of a call," Roddick said.

"To be fair, I didn't come in here (press conference) until 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."

Roddick said his beef was that the out-call came after he had let the ball pass.

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

Roddick added that it was part of his nature to challenge what he feels is not right.

"I don't do it for entertainment. I do it because I strongly believe what I feel," he said.

"That's not just on the court. I think if I believe in something strongly enough, I'm pretty outspoken about it."

But despite his initial rush of blood, Roddick said the Hawk Eye adjudication technology was fair.

"It definitely puts less pressure on them (umpires) as far as having to stick your neck out there," he said.

"But I'm still a fan of Hawk Eye because there's always going to be some judgment calls.

"That's like my match today, where they have a split second to make a very important call."

Apart from the late controversy, Roddick was satisfied with his work against the Brazilian left-hander.

"I felt good out there today. With him it's a lot of just trying to keep the ball out of his hitting zones because he hits pretty big," he said.

"Keeping the ball on the backhand side, which is a little trickier, because he's a lefty.

"It was just a matter of kind of getting the ins and outs of the points. I thought I did a pretty good job of that."

The American was always in control and broke the Brazilian's service four times, while only conceding one break on his own serve.

His next opponent will be Spaniard Feliciano Lopez, who beat former Australian Open finalist Rainer Schuettler in four sets.

Roddick is now 7-0 for the new season after winning the leadup Brisbane International tournament earlier this month.