Right now, the Nats lead the Reds by .5 games. That half game is one Reds loss, with the Reds at 92-60 and the Nats at 92-59. Nats today trailing 2-0 to Brewers in the fourth inning. The Nats and Reds will get even in games played tomorrow, Monday, when the Nats play the Brewers and the Reds are off.
The Nats play at the Phils, at the Cards, and home v. Phils. Reds play Brewers at home, Pirates on road, Cards on road. The Nats won the season series against the Reds and would win a tie-breaker.
Of course, the winner of the best record race plays the wild card. The "loser" plays the division winner with the third best record.
Right now, that third best division winner is the Giants. The Giants are a hot ballclub having won 9 of 10. The Giants are 89-63 so they trail the Reds by 3 and they trail the Nats by 3.5.
Giants also have a day off tomorrow, then they play the DBacks at home, then finish on the road against the Padres and Dodgers.
If the Brewers give the Reds trouble and the Phils do well at home against the Nats, it's possible that by next weekend we could have a close three-way race for the top positions in the NL playoffs. As a Reds fan, it's nice to have such matters to think about.