A cagey contest with a tentative Tewa Kiram saw the crowd restless from the second round onwards and it looked as though the Thai visitor would see out a points win in California.
That was until the hardened Argentinian finally connected in the eighth to drop Kiram and leave the writing on the wall for the previously undefeated Asian.
Matthysse immediately jumped on Kiram after he’d taken the mandatory eight count before scoring with an even better punch to completely lay his opponent out.
Referee Raul Caiz Sr. didn’t even bother to make it to ten before waving the contest off and advising Kiram to stay down for a couple of minutes.
It wasn’t a fan-friendly encounter by any stretch of the imagination but Matthysse finally has the world title he wanted and can potentially seal a big pay day before retirement.
In the co-main, Jorge Linares took just two rounds to figure out Mercito Gesta as the Venezuelan pushed towards a unification against Mikey Garcia in the summer.
The 32 year-old was slow out of the blocks but made the necessary adjustments after six minutes and proceeded to win eight of the next ten rounds on the WBN Scorecard.
Gesta was never overawed by Linares, although lacked that cutting edge you need at the top level and drops a second loss from his 35th career bout.
Judges carded 118-110 (twice) and 117-111 in favor of the WBA lightweight champion who has been ordered to negotiate with Garcia from March 12.
Vasyl Lomachenko has also been sounded out as a possible opponent, although more is set to develop once Garcia fights Sergey Lipinets at 140 in six weeks time.
