After a patchy start, the Swiss looked sharp on the grass as he prepares for his title defence at Wimbledon later this month.
Federer, five-times champion at Halle, will take on Russian Youzhny, who outclassed former Wimbledon semi-finalist Richard Gasquet of France 6-3, 6-2.
“I felt good out there, and as I had predicted it was a tough match,” Federer, the world No.3, said. “I have not won a title this year, twice I have lost here in the final in the past years. It will not be easy but I am really looking forward to it.”
Federer’s unusually erratic forehand earned 35-year-old Haas his first break points at 3-2, and another long crosscourt forehand by the Swiss gave the world No.11 a two-game cushion.
Haas, whose 2012 Halle final win over Federer was his first in ten years against him, saved two break points at 5-2 to serve out the set when Federer pushed another forehand long.
The tables were turned in the second set, with Federer racing to a 3-0 lead after breaking Haas, whose injury-free season has seen him win in Munich and reach the French Open last eight. After drawing level, Federer went 3-1 up in the decider when Haas double-faulted twice in a row, and the 31-year-old clinched victory on his second match point.
“It would be very nice to win any title during the season, because it gives you incredible confidence,” he said. “You know that you’re on the right track, you know you’re doing the right things, the hard work is paying off and your scheduling seems to make sense. Winning tournaments is everything. For me, it would be great to win the final. It comes at the right time.”
Youzhny, who has lost all 14 past encounters against Federer, enjoyed a more comfortable afternoon, breaking Gasquet early on to race to a 4-1 lead in the first set. Two quick breaks in the second took him away from the Frenchman, and the world No.29 wrapped it up in just under an hour for his first final appearance of the year.
Also in Germany, Simona Halep won her first WTA title when she beat Andrea Petkovic 6-3, 6-3 to win the inaugural Nurnberger Versicherungscup. The seventh-seeded Romanian had six aces and broke for a 2-0 lead in the second set of the clay-court final. She fought off two break points in the last game before closing out the match with two forehand winners to win the first of four career finals.
Petkovic, a German wild card, was in her first final in more than 20 months after injuries and was seeking her third title. A former top-10 player, Petkovic is on the comeback trail. “Simona played incredibly and I was a little tired,” Petkovic said. “Still, I had a good week.” In Birmingham, Croatian teenager Donna Vekic reached her second career WTA final when she beat 2009 champion Magdalena Rybarikova of Slovakia 7-6 (5), 1-6, 6-3 in the Aegon Classic at Edgbaston.
Vekic, who turns 17 in two weeks, also beat Rybarikova en route to her first final in Tashkent, Uzbekistan, last September in her main draw debut on tour. That was also the last time she passed the second round in a WTA event until this week.
Vekic will meet either another Slovak, Daniela Hantuchova, or Alison Riske of the United States in today’s final.