Top prospect Francisco Mejia is expected to make his first start for San Diego on Thursday when the Padres open a four-game series against the host Cincinnati Reds. Mejia, who is rated as the No. 1 catching prospect by MLB pipeline, was acquired from the Cleveland Indians in July for two-time All-Star left-hander Brad Hand and right-hander Adam Cimber.

Going into the season, this weekend’s four-game series between the Washington Nationals and the visiting Chicago Cubs looked like it would be a pivotal one between pennant contenders. It turns out it’s a big one for the Cubs but more of a last gasp for the Nationals, who are barely clinging to their slim postseason hopes as the series begins Thursday.

The Cleveland Indians shook off a three-game funk with consecutive victories and look to post their 80th win of the season when they open a four-game set against the host Toronto Blue Jays on Thursday. The Indians are cruising to the American League Central title and their magic number to clinch stands at eight.

The Arizona Diamondbacks needed to catch their breath after losing eight of 11 games, and the combination of Tuesday’s victory over San Diego followed by a day off provided what they hope is a spark entering Thursday’s opener of a four-game home series with the Atlanta Braves. The series could be a playoff preview considering the Braves lead the National League East and Arizona sits within striking distance in the NL West, but both teams have stumbled lately.