His replacement will be Migthy Mo.
Catinas vs Mo will be interesting - both have HUGE power in their fists. The one who strikes first, will take this.
Right you were, hopefully we can stop talking about replacements with this one if we're lucky, this article confirms but share opinion as well:
As we reported earlier this week, former UFC Heavyweight champion Andrei Arlovski will NOT be making his much discussed K-1 debut at the Final 16 this weekend. Kombat.ro has now revealed that it will be Mighty Mo taking Arlovski's spot against Raul Catinas in the Final 16. Kombat.ro has been a reliable source for fighter announcements in the past, so even though K-1 has yet to make this official (or even change their page to reflect the Ray Sefo/Ruslan Karaev swap), I would consider this a done deal.
Mo is a weird choice for this slot. A few years ago, Mo had the knockout power and aggression to be a real player in K-1, as best shown by his stunning KO victory over Hong-Man Choi back in 2007. But those days are behind him now. He's 2-7 in his last 9, and is coming off a definitive KO loss to Sebastian Ciobanu in the semi-finals of the Bucharest GP. He's simply not the fighter he once was, at even at his best he only qualified for the Final 8 once, in 2004.
What he does have going for him is name recognition and popularity. He's also American, and K-1 has made some efforts this year to establish an American representative - a smart move now that their shows are seen in America on HDNet. So it's not entirely shocking K-1 would turn to him, even if he won't be a factor.
The big winner here is Raul Catinas - I see no reason Catinas does not take the win here, earning himself an unlikely spot in the Final 8. This could be a breakout performance for Catinas, a rising prospect who has suddenly found himself in the spotlight.