Japanese grand champion Kisenosato opened the 15-day Kyushu Grand Sumo Tournament with a loss to Takakeisho on Sunday.
Kisenosato, who entered a tournament as the sole yokozuna for the first time, chased the 22-year-old komusubi around the ring to get a hold of his belt.
Takakeisho, however, fought back and slapped Kisenosato down with his left hand to improve his record against the grand champion to 3-2.
"I was able to give my best in our previous bout (in September) so I tried to do the same here," said Takakeisho, who belonged to the now-defunct Takanohana stable.
"I'm just going to perform what I have learned. I'm focused on doing my best every day."
Kisenosato is aiming for his first championship since March 2017, when he made his debut at the sport's highest rank. The 32-year-old will face top-ranked maegashira Myogiryu (0-1), against whom he holds a 16-4 record.
The three ozeki wrestlers had mixed fates on Day 1 at Fukuoka Kokusai Center.
Takayasu posted a quick and easy win over Myogiryu before Goeido, competing in his 26th straight meet in the sport's second-highest rank, defeated top-ranked maegashira Hokutofuji in the day's penultimate bout.
Tochinoshin, who is fighting in his third meet since being promoted, lost to No. 2 maegashira Tamawashi in a bout lasting only three seconds. The Georgian reached for Tamawashi's belt, but was unable to resist Tamawashi's slaps and stepped out of the ring.
(Tochinoshin loses to Tamawashi)
"I'm glad. The support from the audience allowed me to beat him. I'm going to stick to the basics here so I think I'll do better than the previous meets," said Tamawashi, who had a 4-11 record in September.
Sekiwake Mitakeumi, who won his maiden championship in July, suffered a loss to No. 2 Tochiozan, who twisted the fan-favorite down for the win. Ichinojo was on the backfoot against No. 3 maegashira Nishikigi but the 227-kilogram sekiwake resisted and edged him out.
Kisenosato is fighting at the top rank alone here following withdrawals from Mongolians Hakuho and Kakuryu.
Hakuho, who earned a record-extending 41st championship in September, will likely miss the entire tournament since he needs about five weeks to recover from a right knee surgery underwent last month.