Freytes’ winner, his first goal for the Brazilian club, came 17 minutes after teammate Nonato leveled during a contest where the lead twice changed hands.
John Arias also scored from an early free kick as Fluminense moved even on points and goal difference with Dortmund at the Fifa Club World Cup, ahead of their group finale against Malmelodi Sundowns on Wednesday.
Jinhyun Lee and Um Won-Sang scored for Ulsan, which was eliminated with the result.
Freytes put Fluminense in front for good after the South Koreans failed to clear a corner, dispatching a composed finish inside the right post after receiving German Cano’s tidy pass.
Nine minutes later, Keno’s header of Arias’ cross against a clearly fatigued Ulsan defence sealed the victory.
Ulsan struck twice inside the final 10 minutes of the first half to turn an early deficit into a halftime lead before Fluminense levelled at 2-all through Nonato in the 66th minute.
After a flowing move from the Brazilians, Keno’s cross from the left was only partially cleared, and Nonato delivered a composed finish inside the right post from about 15 yards out.
Late in the first half, Lee leveled for Ulsan in the 37th minute on an exceptional counter attack. Darijan Bojanic’s initial pass from just beyond his own box sprung Won-Sang down the right. Won Sang’s low cross rolled all the way across the box and beyond goalkeeper Fabio’s dive before Lee met it on the opposite flank. From a tight angle, Lee delivered an excellent first-touch finish into an open goal.
It was the same duo connecting in reverse in first-half stoppage time, when after a poor Fluminense partial clearance, Won Sang met Lee’s cross with a powerful diving header beyond Fabio’s dive into the bottom left corner.
For the opening half-hour it was Fluminense who looked far more likely to score. The lead eventually came through Arias in the 27th minute on his ferociously struck right-footed free kick from 25 yards that beat goalkeeper Jo Hyeon-Woo to the top right corner. (Reuters)
