Simsri (41-1, 36 KOs) scored a pair of second-round knockdowns against a visibly hurt challenger Mark Vicelles before referee Koji Tanaka waved off their main event contest at Fujisanmesse in Fuji, Japan.

The stoppage came at 2:10, as Simsri reeled off a second consecutive early stoppage since edging a split decision against Cristian Araneta for the title last June.

Guilty of getting too comfortable in the pocket after an encouraging first stanza, Vicelles (21-3-1, 11 KOs) paid the ultimate price.

A three-punch combination foreshadowed a furious finish, though the Filipino couldn't get out of the way of the champion's ire as a straight right hand floored him moments later.

Vicelles stumbled to the canvas after absorbing a straight right to the head 30 seconds later, before clubbing punches at close-range prompted him to slug it out with his back virtually against the ropes.

While he did land some resistance, that proved his last hurrah, as Simsri teed off punishment and chained together a flurry which rocked him and forced the official to swiftly step in.

Simsri told The Ring's Anson Wainwright last week that while impressed by Regie Suganob's stoppage win over Sivenathi Nontshinga, he's more interested in title unifications at 108 pounds. It's a quicker way to create the legacy he seeks for Thai professional boxing, as routine championship defenses against underdogs isn't enough.

Suganob (19-1, 8 KOs) avenged his only career defeat by Nontshinga on September 12 and The Ring's No. 5 strawweight is next in-line as Simsri's latest IBF mandatory challenger.

WBA beltholder Daiya Kira (5-0, 4 KOs) will box 'champion in recess' Rene Santiago (16-4, 9 KOs) at some stage after an elbow injury prevented the latter from making a mandatory defense.

Santiago, who is back in full training, holds the WBO crown too.

WBC champion Shokichi Iwata (17-2, 14 KOs) stopped Erik Badillo on July 20 and his name has been teased, among other titlists, to be unveiled as part of a fight card announcement Tuesday midday local time in Japan.