Hammel looks to avoid a fourth loss in as many starts for the visiting A's in Wednesday's decisive series finale against the Houston Astros.
After allowing four runs in 6 2-3 innings before the A's rallied to win 7-4 on Tuesday, Samardzija is 2-1 with a 3.19 ERA in five starts since Oakland (66-40) acquired he and Hammel (0-3, 7.11 ERA) from the Chicago Cubs on July 4.
Hammel went 8-5 with a 2.98 ERA in 17 starts for the Cubs, but has yielded 19 hits and seven walks in 12 2-3 innings for the A's. Though Oakland has given Hammel just three runs of support, the right-hander won't make excuses.
''The easiest thing here is to start getting down on myself, but I'm not going to do that,'' he said. ''Just got to make quality pitches."
Hammel's teammates felt there was enough to build on from his longest outing with the A's on Friday, when he gave up four runs in 5 2-3 innings at Texas.
"He's always been a really effective guy," shortstop Jed Lowrie said. "I think he's going to start locating that stuff and help us where we want to go."
Hammel hasn't faced the Astros (43-64) since 2011, but is 2-1 with a 1.69 ERA in four starts against them.
Yoenis Cespedes had three hits and Brandon Moss snapped an 0-for-14 slump with a go-ahead RBI single that highlighted the A's six-run ninth inning Tuesday. Oakland bounced back from a 7-3 loss Monday to hand Houston its sixth defeat in seven games.
''Any time you lose games in the eighth or ninth inning, those are tough games to lose,'' Astros manager Bo Porter said.
Cespedes is batting .357 with 11 RBIs in 10 games following the All-Star break, which he entered on a 2-for-41 slump.
He's hitting .409 with 13 RBIs in his last 11 games against the Astros, and is 5 for 6 with a double versus Dallas Keuchel (9-7, 3.11).
Though the left-hander is 0-2 with a 6.23 ERA in four starts against the A's, he allowed three runs and struck out six in 6 1-3 innings of a 7-6 home win April 26.
Keuchel was 1-3 with a 6.07 ERA during a five-start stretch before allowing two unearned runs and striking out seven in seven innings of a 2-0 loss to Miami on Friday.
"I think I've been pitching well, it's just the results haven't been there," he told MLB's official website. "You go through stretches like that as a pitcher. Even position guys do the same thing. The mental aspect of this game is tough, and like I said before, the tough survive, and I'm right there."
Houston All-Star Jose Altuve is batting .408 during an 11-game hitting streak, and .386 while hitting safely in 16 straight against the A's.
He's 1 for 3 versus Hammel.