The NL Central will send two teams to the playoffs, and bettors are keenly observing which of the Pirates or Cardinals will advance as the division champ and which will be a Wild Card entry.
The Pittsburgh Pirates can leap-frog the St. Louis Cardinals this weekend as the rivals embark on a weekend betting series in Pittsburgh starting Friday night.
And St. Louis has had a hard time handling Pittsburgh in their MLB betting matchups so far this year, winning just five of the 13 games between the two teams over the first five months of the season.
"We expect our MLB betting lines will reflect that historical fact later this week," said Kevin Bradley of Bovada.
The Cardinals had started just 2-7 in their first nine games against the Pirates in 2013 before winning three of their last four meetings. Totals bettors have watched the OVER/UNDER go 8-4-1 in Cards/Pirates matchups.
With just over a month left in baseball's regular season the Cardinals sit at 4/1 on the odds to win the NL Pennant, according to Baseball Odds, putting them just ahead of the 9/2 Pirates on those MLB futures. The third NL Central contender, the Cincinnati Reds, sits at 13/2 odds.
The Los Angeles Dodgers headed into action on Tuesday night as the 8/5 leader on the NL Pennant odds at the sportsbooks, with the Braves next at 3/1 odds.
Over in the American League there are more contenders for playoff berths right now, with eight teams all holding down respectable pennant odds at the sportsbooks - the Tigers (9/4), Red Sox (4/1), Rangers (5/1), Rays (11/2), Athletics (13/2), Orioles (10/1), Yankees (12/1), and Indians (16/1). Each is still a contender for at least a Wild Card.
And six of those teams will meet in a trio of marquee MLB betting series this weekend, with Baltimore at New York, Tampa Bay at Oakland, and Cleveland at Detroit. The Indians entered Tuesday's action 5.5 games behind the Tigers in the AL Central division standings, but just two games behind the A's for the final Wild Card berth.
Cleveland, however, has been brutal against Detroit so far this season, winning just three of their 16 meetings for their supporters on the MLB odds and going just 1-12 in the last 13 games between the AL Central clubs.
The OVER/UNDER has gone 9-7 in games between the Tigers and the Indians for totals bettors so far this season.
Sunday Night Baseball this week features a pair of NL East teams, with the Washington Nationals playing host to the New York Mets.
The Nationals, on the fringes of contention in the NL Wild Card race, are 7-5 against the also-ran Mets so far this season, with the OVER paying out for totals bettors in seven of those contests.
See current MLB lines here at SBNation.