The defender was then shown a direct red card in the 67th minute for bringing down Luka Jovic, when the striker looked to be through on goal to leave Betis with 10 men.
"It's a bit cold tonight, I didn't get used to the field and the weather. I gradually adjusted myself and did better than I usually do," Song added.
Flamengo had asked the Brazilian Football Confederation (CBF) to postpone the clash after reporting at least 16 positive coronavirus cases in their first-team squad, with only nine outfield players available.
Elsewhere, last season's fourth-placed side Lazio enjoyed a 2-0 away win over Cagliari with goals from Manuel Lazzari and Ciro Immobile.
The result at the Maracana stadium lifted Flamengo to the top of their group with 12 points from five matches, three points ahead of second-placed Independiente.
Also on Tuesday, men's singles seventh seed Matteo Berrettini of Italy cruised to a 6-3, 6-1, 6-3 victory over Canadian Vasek Pospisil.
Other key matches this weekend saw Chelsea fight back from 3-0 down to take a 3-3 draw away to West Brom, while Manchester United won 2-1 away to Brighton and Everton maintained their 100 percent start to the season thanks to a 2-1 triumph away to Crystal Palace. Enditem
Dalian had the chance to score the equalizer but Salomon Rondon's free-kick smacked the woodwork.
The Serbian, who is seeking his 18th grand slam title, will face Colombia's Daniel Elahi Galan in the next round.
Sunday's last game saw Jarod Bowen score twice as West Ham claimed their first points with a 4-0 win at home to a lackluster Wolverhampton Wanderers. Wolves' striker Raul Jimenez scored a 66th minute own goal and Sebastian Haller bagged the fourth in injury time.
Striker Bi Jinhao scored a brace in the first half to seal the win for the Shanghai side in the last round of the first CSL phase.