UPDATE: Boxing News editor Tris Dixon has this from Murray's trainer Joe Gallagher:
The fight is almost definitely still on.
* * * * *
Despite a series of attempts to make the lightweight limit for tomorrow's fight with the UK's John Murray, WBA lightweight titleholder Brandon Rios has run out of time to make the 135-pound limit for the fight, and has effectively lost his title on the scales.
Rios weighed in at 136.6 pounds on his final attempt, which came one hour after the official weigh-in.
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The 25-year-old Rios has always been known as a big lightweight, and has been well-known as someone who really has to drain down hard to make weight for his fights. He's not quite on the level of someone like Ricky Hatton for inflating between bouts, but it's sort of the same idea: Rios isn't one of those guys who stays in constant shape. But even if he were, most seemed to feel, including his handlers and trainer, that his days at 135 pounds were limited.
Now, they're definitely over.
The fight will still go on, it appears, though it will only be a title fight for John Murray. If Murray wins the fight, he gets the belt. If he does not, the title becomes vacant. Either way, Rios has lost his title, and will surely be moving up to either the junior welterweight or welterweight division after this.