MELBOURNE: Rafael Nadal and Andy Roddick took an easy road to the third round at the Australian Open on Wednesday with routine victories that kept them on track for a semifinal showdown at the season's first Grand Slam. The thread that ties them together from 2009 — Roger Federer, who beat Roddick in the semis last year before losing to Nadal in the final — will likely still have something to say about who the eventual champion is on Jan. 31. The top-seeeded Swiss star is on the other side of the draw and couldn't meet either Nadal or Roddick until the final. Nadal breezed to a 6-2, 6-2, 6-2 second-round win over Lukas Lacko of Slovakia while Roddick was equally untroubled by his opponent in a 6-3, 6-4, 6-4 win over Brazil's Thomaz Bellucci. Roddick, however, had some problems with the chair umpire, Fergus Murphy of Ireland, over a disputed call at a critical time that was ruled out when it was eventually shown to be in. Roddick felt he possibly could have returned the ball if it had not been called out, and let the umpire know in no uncertain terms. The Hisense Arena crowd didn't appreciate Roddick continuing the verbal jousting with Murphy after the match ended and booed the American. The former No. 1-ranked Roddick took time to review video after the match, and was conciliatory in a news conference that followed. "To be fair, I was more wrong than I thought I was out on court," Roddick said. "It was a lot closer than I thought as far as when the call came. I thought I was going to be 100 percent right." Nadal, who converted five of his first six break-point chances, had no such dramas. "I played a serious match. I think I played the match I needed to play," the six-time Grand Slam winner said. "I was playing, moving well in the beginning without mistakes, having control of the ball." Two men with potential to derail a Nadal-Roddick semifinal were scheduled to play later Wednesday — U.S. Open champion Juan Martin del Potro and No. 5 Andy Murray — in second-round matches. No. 4-ranked Del Potro, who could play Roddick in the quarterfinals, was to face American James Blake, while Murray, who could meet Nadal in the quarters, faced Marc Gicquel. No. 11 Fernando Gonzalez of Chile, the 2007 runner-up, is already into the third round after beating Turkey's Marsel Ilhan 6-3, 6-4, 7-5. American John Isner had a 6-3, 7-6 (4), 7-5 second-round win over Louk Sorenson, who on Tuesday became the first Irishman to win a Grand Slam main draw match. U.S. Open champion Kim Clijsters, a 6-3, 6-3 second-round winner over Tamarine Tanasugarn of Thailand, was to find out later Wednesday whether another showdown with fellow Belgian comeback player Justine Henin is in the cards. Henin, who faced a tough second-rounder against No. 5-seeded Elena Dementieva later Wednesday, could play Clijsters in the quarterfinals. The two met in the Brisbane International final nearly two weeks ago, with Clijsters winning in Henin's first official tournament after 20 months in retirement. Clijsters had a few words of warning for Henin after admitting that she doesn't always play her matches "conveniently, but good enough." "But when I had to play well against Justine, I was able to really raise my level," Clijsters said. "That's something that obviously after having been off for a long time, it takes time to get that. I was happy I was able to do that against Justine, and at the Open last year as well." Next up for the 26-year-old Clijsters will be No. 19 Nadia Petrova, one of the Russian women already into the third round along with French Open champion Svetlana Kuznetsova, last year's Australian Open runner-up Dinara Safina and Maria Kirilenko. No. 16-ranked Yanina Wickmayer, a Belgian who didn't get a seeding here because her suspension for a World Anti-Doping Agency "whereabouts rule" violation hadn't been overturned before entries closed, reached the third-round with a 7-6 (2), 6-1 win over No. 12 Flavia Penneta of Italy. Third-ranked Kuznetsova was first into the third round when she beat Anastasia Pavlyuchenkova 6-2, 6-2. No. 2 Safina had a 6-3, 6-4 win over Barbora Sahlavova Strycova — saving four break points in the last game before serving it out. Kuznetsova, who has two Grand Slam singles championships — adding the French last year to her win at the 2004 U.S. Open — has a chance to reach the No. 1 ranking for the first time if she takes the Australian Open title. "Yes, definitely, I know all the way how to go — I've done it twice," Kuznetsova said of her chances of winning a major. She's never gone past the quarterfinals in Melbourne." Safina has held the No. 1 ranking but never won a major. She next plays Britain's Elena Baltacha, who has already equaled her best run at the season's first major by reaching the third round with a 6-2, 7-5 win over No. 30 Kateryna Bondarenko.