LAS VEGAS -- It was hardly a vintage Jon Jones performance. In fact, it was probably one of the most lackluster efforts in his long reign as UFC light heavyweight champion.
In the end, though, it was enough for Jones to win a split decision against a very tough Thiago Santos and retain his title in the main event of UFC 239 on Saturday night at T-Mobile Arena.
Two judges scored it 48-47 for Jones, and a third judge had it 48-47 for Santos.
This was the first time in Jones' career in which he had gone to a decision and was the loser on a judge's scorecard. The only time Jones lost was in 2009, when he was disqualified in a fight against Matt Hamill because of the use of illegal elbows.
Jones acknowledged afterward that Santos made him look "bad" and that Santos' strategy of focusing on leg kicks to Jones' calf was very effective.
"He did a really good job," Jones said. "He exploited a hole in my game, and that's something that won't be there next time."
Despite the nature of the victory, Jones set a UFC record for the longest unbeaten streak at 17 (16-0 with one no contest). Jones tied Georges St-Pierre for the most UFC title wins at 13.
Santos said he injured his left knee in the first round, and he seemed to favor it throughout. However, Jones never realty took advantage of it and pushed the action, probably out of hesitation because of Santos' prodigious punching power.
"I am so sorry," Jones said afterward in the cage. "I know you guys are booing me. We all know that his best chance was to win by knockout. I played it smart."
Judge Mike Bell had Jones winning the second, third and fourth rounds. Derek Cleary had Jones winning the second, third and fourth. Junichiro Kamijo, the judge who awarded the fight to Santos, had Santos winning the first, second and fourth.
It was a close fight throughout. Santos had moments in the first two rounds, particularly with his kicks. In the second, Santos landed a head kick that Jones seemed to take without much damage.
Santos landed a hard combo on Jones in the third but also fell to the canvas coming in for a striking exchange. It was unclear whether Jones did any real damage in that moment or if Santos just slipped. Jones landed a nice head kick and just grazed Santos with a flying knee in the third as well.
In the fourth, Santos landed a big left hand on Jones. Jones took over toward the end of the round as Santos' leg injury became more noticeable. Santos was clearly injured in the fifth but did the most damage with his kicks and punches.
Jones never really went for a takedown and did not utilize his superior wrestling.
"I felt like I was winning, so there was no need to take him down," Jones said. "We were playing a very high-level game of chess in there. Any time you out-kickbox a black belt in Muay Thai, you shouldn't hold your head down."
Jones (25-1, 1 NC) has won three straight bouts since returning from a 15-month suspension for a failed drug test. The resident of Albuquerque, New Mexico, regained the UFC light heavyweight title that was stripped from him by beating Alexander Gustafsson via third-round TKO at UFC 232 in December.
Jones, 31, has been in seven five-round decision victories. He landed at least 92 significant strikes in the first six of those fights, but on Saturday he landed only 59 of 90 (65 percent); Santos landed 43 of 166 (25 percent).
Santos (21-7) had won four straight coming in, including his past three since moving up to light heavyweight, all by finish. The Brazilian slugger had won eight of nine fights overall before this defeat. Santos, 35, lost only his second career fight by decision.