The fight announcements for October's quickly filling UFC 121 event continue to come at a rapid pace, as two more heavyweight matchups are the latest additions to the card.

The additions include former UFC heavyweight title challenger Gabriel Gonzaga taking on "The Ultimate Fighter" 10 cast member Brendan Schaub and Todd Duffee looking to get back on the winning track against H.I.T. Squad-trained fighter Jon Madsen, according to MMAjunkie.com.

Gonzaga (11-5) is 1-2 in his last three bouts, suffering first-round TKO losses to Shane Carwin and most recently Junior dos Santos at UFC on Versus 1 in March. The Brazilian heavyweight sports a 7-4 record in 11 fights with the UFC, with notable Octagon wins coming against Kevin Jordan, Justin McCully and Mirko "Cro Cop" Filipovic. His other UFC losses have came against Randy Couture and Fabricio Werdum.

Schaub (6-1) is currently on a two-fight winning streak, scoring back-to-back first round TKO wins over Chase Gormley and most recently Chris Tuchscherer at UFC 116 earlier this month. Prior to the wins, he suffered his first career loss against Roy Nelson in his Official UFC debut in the finals of the TUF 10.

Duffee (6-1) was recently dealt the first loss of his young career in his last bout, as he suffered a memorable third round knockout loss to Mike Russow at UFC 114 in May. He previously won the first six bouts of his career including a stunning seven-second knockout win over Tim Hague in his Octagon debut at last August's UFC 102 event.

Madsen (6-0) is fresh off an unanimous win over Karlos Vemola at UFC 116 on July 3. The win moved him to a perfect 3-0 UFC record, with previous Octagon wins coming over Mostapha Al-Turk and Justin Wren.

The as-of-yet announced UFC 121 event takes place on October 23 at the Honda Center in Anaheim, California.

The event will likely be headlined by a UFC heavyweight title bout between current champion Brock Lesnar and top contender, Cain Velasquez. In addition, former Strikeforce middleweight champion Jake Shields will make his much anticipated UFC debut against rising welterweight contender Martin Kampmann.

Make sure to check back with us the day of the event for free, live, round-by-round coverage of UFC 121 right here at FiveKnuckles.com! Join expert analyst Mike Williams as he takes you through the entire fight card blow-by-blow and then keep it right here for all the post-fight news and notes you can handle!