On April 3, 2010, a 38-year-old John Ruiz (44-8-1, 30 KOs) got a shot at the heavyweight WBA title held by 29-year-old British boxer David Haye (23-1, 21 KOs).
Ruiz came in to the fight on a 1-fight win streak with a 56% KO rate, and was fighting after a gap of 4 months and 27 days. Haye was on a 13-fight win streak with a 87% KO rate, and fighting after a layoff of 4 months and 27 days.
David Haye stopped John Ruiz via TKO in the 9th round of the 12-round world-title fight, and successfully defended his WBA heavyweight title. Haye improves his record to 24-1 (22 KOs), while Ruiz adds a loss to his record at 44-9-1.
On August 30, 2008, John Ruiz and Nikolai Valuev met again in a rematch.
Ruiz came in to the fight on a 2-fight win streak with a 56% KO rate, and was fighting after a gap of 5 months and 22 days. Valuev was on a 2-fight win streak with a 69% KO rate, and fighting after a layoff of 6 months and 14 days.
Nikolai Valuev defeated John Ruiz via unanimous decision in the rematch. Valuev improves his record to 49-1, while Ruiz adds a loss to his record at 43-8-1.
On November 18, 2006, a 34-year-old John Ruiz (41-6-1, 28 KOs) and a 28-year-old Uzbekistani boxer Ruslan Chagaev (21-0-1, 17 KOs) met in the ring.
Ruiz came in to the fight on a 1-fight losing streak with a 58% KO rate, and was fighting after a gap of 11 months and 1 day. Chagaev was on a 16-fight win streak with a 77% KO rate, and fighting after a layoff of 4 months and 3 days.
Ruslan Chagaev defeated John Ruiz via split decision in the 12-round fight. Chagaev improves his record to 22-0-1, while Ruiz adds a loss to his record at 41-7-1.
On December 17, 2005, the 33-year-old WBA heavyweight world champion, John Ruiz (41-5-1, 28 KOs), faced a 32-year-old Russian boxer Nikolai Valuev (42-0, 31 KOs), in a title defense fight.
Ruiz came in to the fight on a 3-fight win streak with a 59% KO rate, and was fighting after a gap of 7 months and 17 days. Valuev was on a 42-fight win streak with a 73% KO rate, and fighting after a layoff of 2 months and 16 days.
Nikolai Valuev defeated John Ruiz via majority decision and wins the WBA title — in his first world-title fight. Valuev improves his record to 43-0, while Ruiz adds a loss to his record at 41-6-1.
On March 1, 2003, the 31-year-old WBA heavyweight world champion, John Ruiz (38-4-1, 27 KOs), faced a 34-year-old Roy Jones Jr. (47-1, 38 KOs), in a title defense fight.
Ruiz came in to the fight on a 1-fight win streak with a 62% KO rate, and was fighting after a gap of 7 months and 2 days. Jones Jr. was on a 13-fight win streak with a 79% KO rate, and fighting after a layoff of 5 months and 22 days.
Roy Jones Jr. defeated John Ruiz via unanimous decision and wins the WBA title. Jones Jr. improves his record to 48-1, while Ruiz adds a loss to his record at 38-5-1.
On August 12, 2000, 28-year-old John Ruiz (36-3, 27 KOs) and 37-year-old Evander Holyfield (36-4-1, 25 KOs) fought for the vacant WBA heavyweight title.
Ruiz came in to the fight on a 11-fight win streak with a 69% KO rate, and was fighting after a gap of 8 months and 1 day. Holyfield was on a -1-fight win streak with a 61% KO rate, and fighting after a layoff of 8 months and 30 days.
Evander Holyfield defeated John Ruiz via unanimous decision . Holyfield improves his record to 37-4-1, while Ruiz adds a loss to his record at 36-4.
On March 15, 1996, a 24-year-old John Ruiz (25-2, 17 KOs) and a 23-year-old Samoan boxer David Tua (22-0, 18 KOs) met in the ring in a heavyweight bout.
Ruiz came in to the fight on a 7-fight win streak with a 63% KO rate, and was fighting after a gap of 5 months and 8 days. Tua was on a 22-fight win streak with a 81% KO rate, and fighting after a layoff of 2 months and 2 days.
David Tua stopped John Ruiz via KO in the 1st round. Tua improves his record to 23-0 (19 KOs), while Ruiz adds a loss to his record at 25-3.
On August 4, 1994, a 22-year-old John Ruiz (18-1, 11 KOs) and Danell Nicholson met in the ring in a heavyweight bout.
Ruiz came in to the fight on a 4-fight win streak with a 57% KO rate, and was fighting after a gap of 1 month and 10 days.
John Ruiz lost to Danell Nicholson via split decision in the 12-round heavyweight fight, and adds an loss to his record at 18-2.
On August 12, 1993, a 21-year-old John Ruiz (14-0, 9 KOs) and Sergei Kobozev met in the ring.
Ruiz came in to the fight on a 14-fight win streak with a 64% KO rate, and was fighting after a gap of 1 month and 18 days.
John Ruiz lost to Sergei Kobozev via split decision in the 10-round fight, and adds an loss to his record at 14-1.