|Vitali Klitschko, right, took twelve rounds to beat challenger Kevin Johnson in Bern [GALLO/GETTY]
Ukrainian boxer Vitali Klitschko claimed a unanimous points victory over Kevin Johnson in Bern to retain his WBC heavyweight title.
The previously unbeaten US challenger was kept on the ropes for much of the fight, only landing a few heavy shots to hurt his 30-year-old victor.
Klitschko (39-2, 37 KOs) was making a third successful defence of the belt he reclaimed in October last year after a four-year break to recover from injuries.
"I would have preferred a knockout but I'm happy because I won all 12 rounds,'' Klitschko told 17,000 fans ringside at PostFinance Arena.
"He's not easy to hit.''
Klitschko is now turning his attention to a potential WBA title fight against Britain’s David Haye.
Klitschko, and his younger brother Wladimir, the IBF and WBO champion, who will never fight each other, want to own all four major titles in 2010 by taking the WBA belt held by Haye.
"We have a dream and we will do our best to make our dream come true,'' Klitschko said.
"It will be very interesting in the next year.''
Haye next has a mandatory defence against John Ruiz, likely to be in London in the spring.
"I wish him good luck,'' Klitschko said.
"If David Haye will be ready to fight any time, I will be here.''
Johnson proved a durable opponent and did his best work with counterattacking straight left jabs, though without managing to rock Klitschko who has never taken a standing count in his career.
"When I first met Vitali I told him, 'You won't knock me out.' It wasn't a hard fight,'' Johnson said.
"There are things we need to work on and we're going to go home to the gym and polish them up.''
|The result was Johnson's first professional defeat in 24 fights [GALLO/GETTY]
Klitschko opted to take the fight just 11 weeks after beating Cris Arreola, another unbeaten American who did not come out for the 11th round of their bout in Los Angeles.
Johnson, the WBC's sixth-ranked contender, experienced his first professional defeat in his 24th fight.
At 6-foot-7 and 247 pounds, Klitschko took a size advantage of 3½ inches and 4lbs into the ring.
Johnson opted for defensive tactics, inviting the champion from Ukraine in the second round to come at him.
Klitschko aimed mostly head shots but a succession of overhand rights found Johnson turning away in defence.
The champion's right cheek was marked in the fourth round, and Johnson connected with a left hook in the sixth.
But Johnson failed to mount many combinations and Klitschko kept winning rounds with steady jabs, more big rights and an occasional straight left.
The fight heated up in the 11th when Klitschko responded to Johnson's taunting hands-spread gesture with a flurry of blows.
In the final round, Johnson pointed at his chin to goad Klitschko into another attack, and the bout ended with the American finally trading punches in the centre of the ring.