Ryan Zimmerman's out of the lineup for the second-straight game dealing with back issues that cropped up after sliding into home during the Nats' recent visit to Miller Park in Milwaukee. After both Zimmerman and Adam LaRoche (back tightness) missed Tuesday night's game, Nats' skipper Davey Johnson told reporters he thought both would return to the field today, but when the lineup was announced this afternoon Zimmerman was still sitting. According to tweets out of Nationals Park tonight, the Nats' 27-year-old third baseman told reporters that he was "99.9%" sure he would be back in for the finale of the three-game series with the visiting Philadelphia Phillies.

In Zimmerman's place at third and hitting third tonight is veteran infielder/bench bat Chad Tracy.

Edwin Jackson gets the start tonigth against Philadelphia. The 28-year-old right-hander is coming off back-to-back strong starts against the Braves and Brewers in which the right-hander surrendered just one run on 13 hits in 14.0 IP, walking three and striking out 13 in a loss to Atlanta and a win over Milwaukee. Jackson's faced the Phillies just once this year, taking a loss in a 4-1 defeat in Citizens Bank Park. At home in the nation's capital this year, E-Jax is (3-3) in eight starts with a 3.35 ERA, 15 walks and 44 K's in 53.2 IP.

• Here's the lineup that will back E-Jax up in his 20th start of 2012:

#Nationals lineup vs. PHI - Lombardozzi 4, Harper 9, Tracy 5, Morse 7, LaRoche 3, Espinosa 6, Bernadina 8, Flores 2, Jackson 1

— Nationals PR (@NationalsPR) August 1, 2012