SAN DIEGO -- The battle for last place -- or next to last, if you are a glass-half-full type -- in the National League West starts in earnest Thursday night at Petco Park.

Until Wednesday night, the San Diego Padres had resided in fourth in the division since July 7.

However, hours after San Diego completed a 2-7 road trip with a 2-0 loss to the Rays at Tampa Bay, Arizona routed the New York Mets 13-5 behind the bats of Yasmany Tomas and Rickie Weeks Jr. to leave both the Padres and Diamondbacks with identical 50-70 records.

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The opener of a four-game series Thursday night will be the first of 10 meetings between the Padres and Diamondbacks over the season's final 42 games. The next seven of those 10 games will be at Petco Park, while the teams' final three games will be played at Chase Field in Arizona.

Of course, there is no reward for finishing fourth in a five-team race.

It has been a particularly disappointing season for the Diamondbacks, while the Padres have already shifted into full rebuild mode.

Since the Padres and Diamondbacks last met on July 6 -- the day before San Diego moved past Arizona into fourth -- the Padres traded away starting pitchers Drew Pomeranz and Andrew Cashner and corner outfielders Melvin Upton Jr. and Matt Kemp.

Several times in the past two weeks, the Padres had six rookies in the starting lineup. Most games feature four rookies in the San Diego starting nine.

"We're going to be looking at a lot of young players between now and the end of the season," said Padres manager Andy Green, who assisted the Diamondbacks in 2015 as the third base coach. "These are opportunities for players."

The Diamondbacks have a 5-4 edge in the season series, including a 2-1 mark at Petco Park.

When the rivalry resumes Thursday night, right-hander Archie Bradley will start for Arizona with right-hander Paul Clemens making his fifth start for the Padres.

Bradley has a 4-8 record and a 4.91 ERA in 17 starts for Arizona this season. In two starts against the Padres this year, he is 1-1 with a 5.40 ERA over 13 1/3 innings.

This will be Bradley's first start at Petco Park in 2016. The 6-foot-4, 24-year-old has pitched much better on the road this season (3-4 with a 3.73 ERA in nine starts) than he has at home (1-4 with a 6.25 ERA in eight starts). He has also struggled since the All-Star break (1-3, 5.46 ERA in six starts).

"My last couple outings have been disappointing," said Bradley, who has given up nine runs (seven earned) on 10 hits, including three homers, over his past 10 innings.

Left-handed hitters have batted .322 against Bradley this season. That could be a problem Thursday night, as the Padres could be starting four left-handed hitters plus switch-hitting third baseman Yangervis Solarte.

Clemens is 1-2 with a 4.03 ERA in eight game (four starts) since San Diego claimed him off waivers from Miami in late June. Counting his two starts for the Marlins this year, he is 2-2 with a 4.73 ERA.

He made his Padres debut on July 4 against the Diamondbacks, allowing an unearned run on one hit in a one-inning relief appearance. His lone win as a Padre came against the Mets in his most recent start, when he yielded three runs in five innings during an 8-6 victory at New York on Aug. 12.