Nadal powered to sweep 11 straight games from a 1-1 tie in the first set, which ended when the 19-time Grand Slam champion forced McDonald to come to the net with a dropshot and then fired a forehand cross-court winner.
There was last second drama as Manchester United got their first win of the season with a 3-2 victory away to Brighton on Saturday thanks to a penalty given after the final whistle.
Striker Issa Alekasir's header in the 88th minute found the back of net and sent the Reds to the competition's next round.
Miguel Angel Russo's men are now four points clear at the top of the Group H standings, with one match remaining before the knockout rounds.
Local favourite Kristina Mladenovic was a victim of a missed call in her first round defeat to Laura Siegemund of Germany on Tuesday.
The ruling was handed down just 10 minutes before the scheduled kickoff at Palmeiras' Allianz Parque in Sao Paolo. The game eventually started more than 20 minutes late, with Flamengo fielding only four regular first-team players.
The defender was then shown a direct red card in the 67th minute on the instruction of VAR for bringing down Luka Jovic when the striker looked to be through on goal.
In case of infections within club ranks, clubs must ensure at least a 13-man squad to compete in games.
Naiman Banner, located on the edge of the Horqin Sandy Land, also China's largest sandy area, has organized three Naadam festivals of this kind. Enditem
To find new faces seems to be much more vital than to beat Dortmund and win this season's fifth title. Enditem
Yao was the title favorite but the 30-year-old failed to clear the bar at 5.30m, although he passed the height of 5.15m in his first attempt.