Former Ultimate Fighting Championship (UFC) heavyweight number one contender Gabriel Gonzaga was riding the momentum of a two-fight winning streak heading into his UFC 146 match-up against Roy Nelson at the MGM Grand Garden Casino in Las Vegas, Nevada, on May 26, 2012.

Now he's just riding the pine.

That's because "Napao" withdrew from the upcoming pay-per-view (PPV) fight card after blowing out his back while training for "Big Country," resulting in pain so severe he was unable to walk following his recent injury.

The Brazilian breaks it down for Tatame.com:

"I was training hard. I was in great shape to get there prepared. The low back pains were so strong. After a four day observation period we didn’t have other choice than inform the event I wouldn’t be able to fight. I’m very upset because it was a really important fight for me, but things happen for a reason. I’ll get over it. The fighting card is great and it’ll change many things in the division. I’m sad I’m out, but I wanna be 100 percent to fight."

Gonzaga recently emerged from premature retirement after consecutive UFC losses to Junior dos Santos and Brendan Schaub in 2010. He came back to win a tune-up fight against Parker Porter via submission in Oct. 2011 and then put his top-notch Brazilian jiu-jitsu skills to work once again when he tapped Ednaldo Oliveira with a rear naked choke at UFC 142 earlier this year.

There's always next time.

In his absence, Dave Herman will step in and take his place against Nelson on the all-heavyweight main card extravaganza, which goes down in just over two weeks.

More on that new bout here.