Ulsan made up for lost time as they began the K League 1 season with a thumping 4-0 win over Sangju Sangmu.
A first-half double from Junior Negrao, including a penalty, was followed by Lee Sang-heon slotting a third goal after 51 minutes and Yoon Bit-garam grabbing a fourth 15 minutes from time.
The final goal of the game was the pick of the bunch, a terrific 20-yard shot into the right corner.
The season was delayed by almost three months due to the coronavirus pandemic but began on Friday when defending champions Jeonbuk Motors beat Suwon Bluewings 1-0.
Chasing a sixth title in seven seasons, Jeonbuk could find Ulsan just as competitive as they proved last season when missing out on the title only on goals scored.
With all games behind closed doors for now, Seongnam did the damage early away to Gwangju on Saturday. A pair of goals from Yang Dong-hyen in the opening 11 minutes - a header followed by a composed finish – secured a 2-0 victory.
Incheon United and Daegu FC played out a goalless draw in Saturday's other match.