Saenchai (born July 30, 1980), formerly known as Saenchai Sor. Kingstar (Thai: แสนชัย ส.คิงสตาร์), is a Thai Muay Thaikickboxer. He won the Lumpinee Championship title in four different weight divisions, along with the WMC and WBC World titles, while mostly fighting above his natural weight; therefore he is considered one of the best pound for pound Muay Thai fighters in the world. Saenchai often gives up 5 lbs. + in weight to find worthy opponents in Thailand. Against foreigners the gulf in skill is so great he will go up as high as 147 pounds, which is 15+ pounds above his best weight. He is known for having excellent ring vision and speed.
Saenchai started learning Muay Thai when he was 8 years old. He decided to start learning Muay Thai in Jockey gym when his friend's elder brother received a prize after a bout. He debuted after training for only a week, and he won his first bout by decision receiving 30 Baht (≒$1).
He started fighting in Bangkok when he was 14 years old, then transferred to Kamsing gym owned by Somluck Kamsing. Kamsing paid 300,000 Baht as a transfer fee. This is the reason Saenchai's ring name was "Saenchai Sor.Kamsing".
When he was 15, Saenchai won the title of Lumpinee stadium championship at super flyweight. When he was 18, he won the title of Lumpinee stadium championship at bantamweight.
In 2002, Saenchai turned to boxing. He debuted as "Sangpetch Patanakan Gym" at featherweight. He fought against Rud 4K Kevkatchewon from Philippines to challenge for the vacant interim title of PABA on November 27, 2003, and he won the title by unanimous decision. In January 2004, he retained his PABA title against Rud.
In 2004, he decided to go back to Muay Thai again.
Saenchai visited Japan twice to fight and Khamsing agreed at those times, but Khamsing disagreed the third time. Although Khamsing tried to stop Saenchai from going to Japan, he went there with some Muay Thai fighters from another gym. Because of this incident, Khamsing broke off relations with Saenchai, and Saenchai moved to Kingstar gym. At this time, Khamsing received 300,000 Baht from Kingstar gym as a transfer fee.  On July 3, 2006, Saenchai fought against Sang-Soo Lim from Korea in Japan. Saenchai was going to fight against Shinya Ishige but he was replaced two weeks earlier as he had been injured during training. Lim was taller 21 cm and heavier 10 kg than Saenchai but Saanchai knocked out Lim at 2R with a right hook.
On July 3, 2009, Saenchai fought against two muay thai fighters in the single bout at Lumpinee stadium. During 1 to 3 round, he fought against Petchboonchu F.A. Group. Petchboonchu tried to attack aggressively at 1R, but Saenchai carried throughout his stamina-saving style and broke Petchboonchu's balance several times. During 4 to 5 round, Saenchai fought against Sakeddaow Petchpayathai. Saenchai controlled his critical distance with front-kicks and middle-kicks and he threw telling blows more than Sakeddaow did. The referee announced Saenchai's victory with unanimous decision after 5R.
On March 14, 2010, Saenchai fought against Tetsuya Yamato from Japan to challenge the vacant world lightweight title sanctioned by Muay Thai Association of America (MTAA) in Los Angeles. Saenchai knocked out Yamato with left high kick at 1R, and won the MTAA title.
On January 21, 2012 Saenchai lost for the first time against a European in Muay Thai rules. The fight took place in Milan Italy against top foreign Thai boxer, Fabio Pinca. Saenchai had beaten Pinca years earlier. Despite going all the way up to 145, Saenchai still put up a good fight, but by the third round the size difference was starting to pay off for Pinca. He used his strength to tie Saenchai up and win a close but controversial decision. Saenchai's streak of 20 or more straight wins against foreign fighters was snapped.
He beat Pakorn Sakyothin by decision at Super Showdown 4 in Glasgow, Scotland on November 10, 2012 and then took a ponts victory over Damian Alamos twelve days later at Best of Siam 2 in Paris, France. Saenchai then defeated Liam Harrison for the third time at Muay Thai Warriors in Macau on December 9, 2012, taking a clear-cut unanimous decision.
He lost to 17-year-old phenom Yodwicha Por Boonsit on points at Lumpinee on May 10, 2013. The pair were set to rematch on June 7, 2013 but a lingering neck injury forced Saenchai out of the bout.
He beat Raphael Bohic by unanimous decision at Muay Thai Warriors: Dabble in Chiang Mai on June 28, 2013 in Chiang Mai, Thailand.
Saenchai ran through a field of overmatched farangs to win the Toyota Vigo Marathon Tournament on July 24, 2013 in Phitsanulok.
Saenchai beat Kongsak Sitboonmee by decision in a rematch at Rajadamnern on August 8, 2013.
It was reported that he would fight Mickaël Piscitello at the WBC World Muay Thai Millennium Championship in Saint-Pierre, Réunion on September 7, 2013. However, he denied ever being on the card.
He lost to Petboonchu FA Group on points at the last ever show held at the old Lumpinee Stadium on February 7, 2014.
Saenchai defeated Victor Nagbe by decision in a -65 kg match at Yokkao 7 in Pattaya, Thailand on February 19, 2014.
He was scheduled for a March 8, 2014 meeting with Irishman Stephen Hodgers at Origins IV at Welterweight (-64.00 kg/141 lb) in Perth, Western Australia. Saenchai was unable to compete, however, as he did not meet certain criteria demanded by the Western Australia Combat Sports Commission and was replaced by Komkit Chanawong.
Saenchai beat Nong-O on points in a three-rounder at the grand opening of the new Lumpinee Stadium on February 28, 2014.
Saenchai defeated Shota Sato via unanimous decision at Hoost Cup: Legend in Nagoya, Japan on March 23, 2014.
He beat Kamen Picken via UD at Combat Banchamek in Surin, Thailand on April 14, 2014.
He defeated Bertrand Lambert via decision at Muay Thai in Macau on June 6, 2014.
He will rematch Yetkin Özkul in a fight for the WMC World Lightweight (-61.2 kg/135 lb) Championship at Monte Carlo Fighting Masters 2014 in Monte Carlo, Monaco on June 14, 2014.