"I could not just rest on the plane as my players did, but distributed some time to analyze opponents' tactics. I was so tired then," Ji recalled.
Vasco dropped to 10th in the standings, having lost four of their past five fixtures.
She continued to post her powerful serving skills on the court as the world No.11 fired six aces and won 77 per cent of her first serves to clinch the victory.
Brazil will also play Peru in another World Cup qualifier in Lima next Tuesday. Enditem
"We can see the improvement from our players in terms of their game mentality," Tianjin coach Liu Hao commented.
"I told them to fight until the end no matter when leading or trailing. All efforts have paid off now," she said. Enditem
First reports speak of the current Formula 2 driver getting offered a seat in Formula 1 for next year's racing series. Rumors talk of Alfa Romeo signing the young German aside from Kimi Raikkonen.
It took the five-time world champions just 16 minutes to find the target, with Paris Saint-Germain defender Marquinhos meeting a curling Danilo cross with a powerful header from the edge of the six-yard box.
Brazil will enter Tuesday's match at Estadio Nacional in Lima on the back of a 5-0 rout of Bolivia while Peru drew 2-2 against Paraguay in last week's opening round of CONMEBOL qualifiers.
The 18-year-old Chang defeated Irish teenager Aaron Hill 4-2 in the first round.
Coutinho, who was also deployed in a more central role by Brazil coach Tite against Bolivia, said his time at Bayern had taught him the importance of a strong work ethic.