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6/8/2014 10:13 P.M. ET

The Week Ahead: Is Polanco's debut on the horizon?

Tigers vs. White Sox, Red Sox vs. O's, Tanaka vs. Iwakuma among big matchups

Will it be this week? It has to be, right? And if it isn't this week, when will it be?

Those questions were asked last week, when reports surfaced claiming that Pirates No. 1 prospect Gregory Polanco would be called up Friday night in Pittsburgh. That didn't happen, so they're being asked again.

What we know is this: At some point in the near future, Polanco, a 6-foot-4, 220-pound 22-year-old outfielder who has been scorching Triple-A pitching to the tune of a .347/.405/.540 line in 62 games after Sunday's action, will be in Pittsburgh's outfield and lineup.

And it might be one of the days in The Week Ahead, although Pittsburgh general manager Neal Huntington remains mum on the subject.

"Our goal is to bring him here when we feel it's the right time," Huntington said. "In an ideal world, we'd like to get him some more plate appearances down there. What he's doing has allowed us to shorten that time frame a little bit."

In team news, a look atop the standings in the National and American Leagues as we start the new week shows us that the best baseball in the land is being played by the Bay.

The Giants have the best record in the NL (and all of MLB) at 42-21, which equates to a winning percentage of .667, or winning two of every three games. The Oakland A's have the top mark in the AL.

In other words, 25 years after the two franchises met in the 1989 World Series, they're sitting as the top seeds for October, and there's reason to believe they'll stay in the driver's seat as the summer gets hotter.

The Giants, for example, beat the Mets on Sunday and have won five games in a row. They have seven games this week, and they're all at home, finishing off a 10-game June stand at AT&T Park.

They'll get four vs. the Nationals and three against the division-rival Rockies, and those teams will have to be at their best if they're going to even temporarily derail this express train, which is winning in every imaginable way lately.

"That just tells you about what kind of team we have," San Francisco outfielder Michael Morse said after hitting a walk-off single to beat the Mets on Saturday. "We find a way. We've been doing it all year. We've been fighting to the last out. ... We don't give up. We truly think that no matter what the score is, we're going to find a way to win."

The A's aren't too bad, either.

They beat the Orioles in Baltimore on Sunday to improve to 39-24 and head back to California this week for three in Anaheim against the Angels. Then they'll head back up the coast to Oakland and play three in a weekend set against the Yankees.

While the Giants have the better record, the A's have scored 128 more runs than their opposition this season, by far the best mark in the Major Leagues.

"We've had several blowouts," A's manager Bob Melvin said Sunday after the A's beat the Orioles, 11-1. "They seem to be the same type of games -- draw some walks, make them throw a lot of pitches, and we score some runs early in the game."

Other good matchups to watch out for this week include the AL Central-rival Tigers vs. the Chicago White Sox in a four-game series at U.S. Cellular Field, which begins Monday, and the Red Sox in Baltimore vs. the Orioles in a classic AL East showdown that also starts Monday.

For a one-game affair with international implications, you can't really do better than what's on tap in Seattle on Tuesday night, though.

The Yankees are in the Emerald City to face the resurgent Mariners, and New York's electric rookie right-hander from Japan, Masahiro Tanaka, will take on the Mariners' own very talented righty starter from the same country, Hisashi Iwakuma.

Both have been excellent this year and both know each other, having played together for the Rakuten Golden Eagles of Nippon Professional Baseball.

Elsewhere around the big leagues, teams will welcome back players from injuries this week.

The Red Sox are happy to have Mike Napoli back at first base after the slugger was out of action since May 25 because of a sprained finger. Napoli hit an opposite-field homer off Tigers starter Anibal Sanchez in his first game back Sunday.

"You're talking about a guy that's mid-20s home runs and nearly 100 RBIs a year ago," Red Sox manager John Farrell said. "That type of production has been missed. … I think any time you can lengthen the lineup with another quality hitter, it's going to be advantageous for us. We're certainly looking forward to Mike being in that spot."

The Dodgers could welcome back outfielder Carl Crawford from the 15-day DL on Wednesday, when he's eligible. Crawford has been working to return after suffering a sprained ankle on May 27.

Doug Miller is a reporter for MLB.com. Follow him on Twitter @DougMillerMLB. This story was not subject to the approval of Major League Baseball or its clubs.