Vientos (ankle) will start at third base and bat seventh in Wednesday's game versus the Athletics.

Vientos missed the previous two contests with left ankle soreness, but he's feeling well enough to give it a go Wednesday. The young infielder has struggled so far at the plate in August, going just 5-for-30.

McMahon is out of the lineup for Wednesday's game against the Diamondbacks.

With the Rockies and Diamondbacks concluding their series with a day game after a night game and with a southpaw (Jordan Montgomery) on the hill for Arizona, the lefty-hitting McMahon will be given a breather. McMahon had a pair of two-hit games against Atlanta over the weekend but has fallen back into his post-All-Star-break lull at the plate so far in Arizona, as he went 0-for-8 with four strikeouts through the first two games of the series. He's now batting just .119 with a 32.1 percent strikeout rate in the second half.

Chaparro went 3-for-4 with three doubles, one RBI and two runs scored in Tuesday's 9-3 win over the Orioles.

According to Jessica Camarato of MLB.com, Chaparro became just the fourth player since 1901 to hit three doubles in his major-league debut. He hit .328 with 23 home runs and 85 RBI at Triple-A this year and should continue to get opportunities to prove himself as a worthy trade-deadline acquisition.

Arenado went 1-for-4 with a solo home run in Tuesday's 4-1 loss to the Reds.

Arenado's 400-foot blast off Hunter Greene in the seventh inning was the only offense the Cardinals could muster Tuesday. It was his first long ball since July 26, but he has gone 15-for-45 with eight RBI so far in August. On the season, the third baseman is hitting .270 with 12 homers, 53 RBI and 49 runs scored across 472 plate appearances.

Candelario went 1-for-3 with a two-run home run in Tuesday's 4-1 win over the Cardinals.

Candelario took Erick Fedde deep in the sixth inning for his 14th long ball at Great American Ballpark. After a disappointing July, he has hit safely in eight of 11 August contests with four extra-base hits and five RBI. On the season, the 30-year-old is hitting .228 with 19 homers, 55 RBI and 46 runs scored across 443 plate appearances.

Tena (thumb) is out of the lineup for Tuesday's game against the Orioles.

Tena was removed from Sunday's game after being struck in the right hand by a grounder and will require an additional day of rest due to an issue with the fingernail of his right thumb. He should be considered day-to-day. Ildemaro Vargas will start at third base Tuesday.

The Nationals selected Chaparro's contract from Triple-A Rochester on Tuesday, Jessica Camerato of MLB.com reports.

Acquired from the Diamondbacks in the Dylan Floro trade, Chaparro is receiving his first major-league promotion after slashing .328/.405/.572 with 23 home runs over 105 games in 2024 at the Triple-A level. The 25-year-old is expected to play regularly while alternating with Juan Yepez at first base and designated hitter. Chaparro is starting at first base and batting sixth Tuesday in Baltimore in his major-league debut.

Vientos (ankle) is out of the lineup for Tuesday's game against the Athletics, Tim Healey of Newsday reports.

The 24-year-old was a late scratch from Sunday's lineup against the Mariners due to left ankle soreness, and he'll sit for a second consecutive game Tuesday. According to Laura Albanese of Newsday, Vientos is expected to be available off the bench and should rejoin the lineup Wednesday. Jose Iglesias will receive a start at third base and bat seventh.

Marte is out of the lineup for Tuesday's game against the Cardinals.

After making 10 consecutive starts at third base, Marte will get the night off Tuesday. In his place, Santiago Espinal will play third and bat ninth. Marte is slashing .179/.218/.299 across 142 plate appearances this season.

Machado is not in the starting lineup for Monday's series opener against the Pirates, Jeff Sanders of The San Diego Union-Tribune reports.

Machado will begin the series in the dugout after going 3-for-14 with two doubles and four RBI in the Padres' three-game weekend series against the Marlins. Since the All-Star break, Machado is slashing .274/.311/.536 with five home runs and 16 RBI across 100 plate appearances. Donovan Solano will man the hot corner and bat fifth against Pittsburgh right-hander Joe Musgrove.