By MATT BEARDMORE
(AP) -- The Colorado Rockies are trying to avoid matching their lowest point of the season.
The Oakland Athletics are already there.
Colorado will try to end a five-game skid - and a seven-game home losing streak in interleague play - Tuesday night when it faces the last-place A's.
Since a 7-1 run May 28-June 4, the Rockies (24-35) have gone winless to fall well off the Los Angeles Dodgers' pace in the NL West. Colorado begins this three-game set after getting swept by the visiting Los Angeles Angels over the weekend.
"This is tough to take when you see the kind of effort that is given every single day," manager Jim Tracy told the Rockies' official website following Sunday's 10-8 loss. "In order for use to stay true to the way we left spring training, we're going to go out there and whatever circumstances show up, we have to defeat those circumstances."
The Rockies, who have been 12 games below .500 twice this season, need some better pitching. Colorado's major league-worst ERA is 5.31 after the club's starters posted a combined 14.64 ERA since the team's last victory.
Tuesday's scheduled starter Jeremy Guthrie (3-4, 6.35 ERA) shoulders much of the blame for that number after yielding a season-high seven runs in 3 1-3 innings of last Tuesday's 10-0 loss at Arizona.
"If I don't make another start here, it wouldn't surprise me," he said. "I will come to work every day as long as I have a jersey and do the best I can."
At least for now, Tracy will stick with the right-hander, who is 1-2 with an 8.87 ERA in four home starts. Guthrie is 2-3 with a 4.54 ERA in seven starts versus Oakland.
While Colorado tries to improve its 0-6 home record against the AL this season, the A's (26-35) arrive in Denver with a 1-5 mark in NL parks in 2012 after getting swept by Arizona over the weekend.
Oakland is a season-worst nine games below the break-even point.
"It is frustrating but it is also nothing to get alarmed about," said left fielder Seth Smith, who spent his first five seasons with Colorado before being acquired in an offseason deal that sent Guillermo Moscoso and Josh Outman to the Rockies. "Just keep plugging away."
The A's, who on the road have dropped four straight and 12 of 15, could use a lengthy outing from Bartolo Colon (5-6, 3.92) after none of their starters lasted more than five innings in Phoenix.
Colon has gone at least six in nine of 13 starts after pitching eight strong innings in Wednesday's 2-0 victory over the Rangers.
The right-hander has faced the Rockies once, lasting 6 2-3 innings in Cleveland's 5-4 victory at Coors Field on June 16, 2002.
A's center fielder Yoenis Cespedes could play in this series after missing the last three games with a strained left hamstring.
Rockies left fielder Carlos Gonzalez is batting .490 (24 for 49) with seven homers and 14 RBIs during an 11-game home hitting streak. He has never faced Colon.
Colorado is 8-3 at home against Oakland, most recently winning two of three at Coors Field from June 19-21, 2006.
Updated June 12, 2012