Sergey Kovalev earned a hard-fought unanimous points decision against Isaac Chilemba to stay on course for a big pay-per-view bout against Andre Ward.
In only his third professional fight in his homeland, U.S.-based Kovalev (30-0-1, 26 KOs) could not produce the knockout performance he wanted at the DIVS Sports Palace in Ekaterinburg, Russia, Monday.
It was Kovalev's poorest performance in his three-year reign as world light-heavyweight champion that will have been encouraging viewing for Ward at home in Oakland. However, Kovalev's status as unified world light-heavyweight champion was never in doubt at the end of 12 rounds and he was awarded scores of 117-110, 116-111 and 118-109.
Malawi-born Chilemba (24-4-2, 10 KOs) recovered from a seventh round knockdown to force Kovalev to go the distance for just the fourth time in his career. Only Bernard Hopkins had managed to go to points with Kovalev in eight previous world title fights after a disappointing and unimaginative display from the Russian.
It also sets up a big bout next against Ward at the T-Mobile Arena in Las Vegas on Nov. 19. Undefeated former super-middleweight world champion Ward (29-0, 15 KO) will have to overcome Alexander Brand (25-1, 19 KOs) on Aug. 6 in his own interim bout before the fight with Kovalev is confirmed.
The fight with Ward has become a more interesting prospect after Florida-based Kovalev failed to dominate the first half of the fight against a plucky challenger.
Chilemba, 29, had lost his previous fight -- controversially on points to Eleider Alvarez in Nov. -- in a WBC world title eliminator. Despite that setback, Chilemba still got his shot at Kovalev's WBA, IBF and WBO world light-heavyweights titles and proved a stubborn opponent.
The challenger got through with some right hands and Ward will have been encouraged to see how Chilemba managed to land in the fourth round when Kovalev was caught coming forward with left jabs.
Kovalev began finding his range and rhythm later in the fifth round but in the sixth was caught flush by a left hook. Kovalev's biggest weapon is his right hand which Chilemba finally found out about in the seventh round.
The Russian followed a straight left with a right to the jaw which left Chilemba staggering across the ropes and down for a count. Had there been more time left in the round, Kovalev might have finished it there and then.
Chilemba was hurt again late in the eighth round after being caught with a left to the chin but Kovalev, looking tired, allowed his opponent to grow in confidence in round ten. Kovalev finished strong, with blood pouring from Chilemba's nose, but his renowned power punching could not force the stoppage that his home crowd wanted.
Kovalev has been based in the United States since turning professional seven years ago and last boxed in his homeland at the same venue five years ago. That bout ended in tragedy when Kovalev's opponent Roman Simakov, who was knocked out in the seventh round, died as a result of head injuries three days later.