Pohang Steelers closed the gap to K-league leaders Jeonbuk Motors to two points with a 2-1 win over Jeju United.
Pohang dominated the first half and were in front after just three minutes. Adrian Chuva broke free down the right and his low cross was turned in by Derek Asamoah at the near post.
Midway through the half, Shin Kwang-hoon pulled the ball back from the byline for Mota to side-foot home to extend Pohang's lead.
Jeju pulled a goal back after 64 minutes as Santos turned inside the area to find the low corner of Pohang's net but the Steelers hung on for a fifth straight win.
"We moved the ball around very well early in the game,'' Pohang boss Hwang Sun-hong said. "In the second half they pressured us and our concentration levels suffered.
"We are not yet thinking about titles or the 2012 AFC Champions League as there are still games and the play-offs remaining.''
Jeju boss Park Kyung-hoon lamented the early goals. "We made mistakes early on and conceded twice. It was always going to be hard to recover from that,'' he said.
Busan I'Park saw their play-off hopes hit as they were defeated 1-0 at home to Gyeongnam FC thanks to a 17th-minute strike from Roni.
In the day's other matches, Daegu FC defeated Incheon United 2-0 thanks to a Song Jae-hon brace while Gwangju FC drew 0-0 with Ulsan Horangi.
Leaders Jeonbuk, who moved into the semi-finals of the 2011 AFC Champions League in midweek, are in action on Monday.