No one has been tougher to get on base against in the AL than Hisashi Iwakuma.
This could present problems for an Oakland Athletics team struggling at the plate.
The Seattle Mariners right-hander will try to send the Athletics a season-high fifth straight loss Friday night in the opener of a weekend series at Safeco Field.
Iwakuma (3-1, 1.61 ERA) has been among baseball's biggest surprises, leading the AL in opponent batting average (.168) and walks plus hits per inning pitched (0.76).
He uncharacteristically walked three Saturday but yielded one run over seven innings to gain an 8-1 victory at Toronto.
Seattle (16-19) has won his last five starts at home, including three this year in which Iwakuma has posted a 0.48 ERA. His stellar season began April 2 when he allowed one run over six innings with seven strikeouts in a 7-1 victory at Oakland, winning for the first time in three starts against the Athletics.
Slugger Yoenis Cespedes is 3 for 6 with two solo homers against Iwakuma. He and the Athletics (18-18) travel west after totaling eight runs and batting .205 while being swept in four games in Cleveland, capped by Thursday's 9-2 loss.
"They're playing great and can't do anything wrong and we're struggling," manager Bob Melvin said. "That's what happens."
Cespedes homered in the first game of the series before going 1 for 11 with four strikeouts in the final three. Jed Lowrie was 2 for 15 in the series, Derek Norris 2 for 11, John Jaso 2 for 10 and Eric Sogard 2 for 9 for the A's, who have seven players on the disabled list.
Oakland is batting .218 and averaging 2.6 runs in May, and Seattle can relate somewhat to those woes. The Mariners are hitting a major league-worst .199 this month, although they are 4-2.
Seattle has been winning thanks to mound efforts like Wednesday's by Felix Hernandez, who went eight innings as the Mariners avoided a third straight loss with a 2-1 victory at Pittsburgh.
While Hernandez is the unquestioned ace of the staff, Iwakuma is developing a reputation of his own that has given Seattle confidence.
"They're unbelievable," second baseman Dustin Ackley told the Mariners' official website. "Any time you go out there, you're like, 'Let's just get a couple runs and these guys are going to cruise.' They are probably, arguably, right now the two best starters in baseball."
Oakland has won all three games started by Daniel Straily (1-0, 5.94), who takes the mound Friday after giving up three runs over 5 1-3 innings and not getting a decision in Sunday's 5-4 victory over the Yankees.
The right-hander yielded four runs over 4 1-3 innings in his lone start against Seattle on Sept. 29. He also yielded two homers in five 2012 at-bats to Kendrys Morales, then with the Angels.
These clubs split their season-opening four-game set in Oakland. Lowrie went 6 for 13 with four doubles while Michael Morse was 6 for 16 with four homers for the Mariners.
Oakland has taken the last four meetings in Seattle.