The Swiss maestro needed only an hour and 39 minutes to overcome the 47th-ranked Romanian 6-2, 6-3, 6-2 under the Rod Laver Arena lights. It was a convincing performance at the end of a day on which just one seed fell out of the men's draw – 2006 finalist Marcos Baghdatis came from two sets down to beat 17th seed David Ferrer 4-6, 3-6, 7-6 (7/4), 6-3, 6-1.
Third seed Novak Djokovic, the in-form Nikolay Davydenko, 2008 finalist Jo-Wilfried Tsonga and last year's semi-finalist Fernando Verdasco all progressed as the reputation for surprises at the season-opening grand slam continued to be undermined.
Robin Soderling, the eighth seed, remains the only player inside the top 12 to have been eliminated after he lost in the opening round. And while the tournament poses as a tight affair, grand slam record holder Federer gave a reminder of his greatness, albeit against clay-court specialist Hanescu.
The Swiss' performance may not have quite been fit for a king, but it certainly delighted Prince William, who made a late entrance to the applause of the near-capacity 14,000 crowd and Federer himself. But such was the speed of Federer's victory charge the Prince saw just five games.
"It was extremely special. For me it was a big honour that he came and watched me," Federer said afterwards. "I've just briefly had a chance to talk to him. I'm not going tell you everything he just said to me. You've got to have a little bit of a secret. But he said he was happy that I played a little bit longer for him, because the match could have ended even shorter."
He added: "I was very happy with the way I played. I moved well and played some amazing shots. It was great."
Earlier, Djokovic, the 2008 winner, overcame his first-set histrionics to defeat Switzerland's Marco Chiudinelli 3-6, 6-1, 6-1, 6-3. The Serbian cut an agitated figure as he lost the opening set and at one point needed a new racquet after crashing it into the court, but eventually turned his aggression into winners – he hit 58 – to overwhelm his opponent.
"Definitely I was frustrated, especially at the start of the match, because he was really giving it to me," said Djokovic, who will play Uzbek qualifier Denis Istomin next. "That was a little issue there, but I managed to make that transition from being defensive to being offensive."
Davydenko proved why he has been considered as a contender to win his first grand slam title as he swept past Illyan Marchenko 6-3, 6-3, 6-0. The 28-year-old is the form player on tour after his success at the ATP World Tour Finals last November and in Doha to start the year – where he beat both Federer and Rafael Nadal – but after his second successive straight-sets win he played down talk he has stronger claims to the title than those two.
"I never think that I am favourite at any tournaments because I know I can also lose not only to top-10 guys, but I can lose also number 15 or 100," he said. "It's depends how you feel. I know I'm a very good player. If I feel good, for sure I can beat everyone." Baghdatis continued his hot streak in Australia to dump Ferrer out in an enthralling match that lasted four hours and nine minutes on Hisense Arena.
The Cypriot is now on a seven-match winning streak after winning in Sydney last week and will next play local hope Lleyton Hewitt, which will evoke memories of their epic five-set match two years ago when the Australian edged to victory at 4.30am.
Hewitt, the 22nd seed, won through by beating American Daniel Young 7-6 (7/3), 6-4, 6-1.
Tenth seed Tsonga only needed three sets to beat Taylor Dent 6-4, 6-3, 6-3 while Verdasco also raced through his night match with Ivan Sergeyev 6-1, 6-2, 6-2.