Hard to believe it's still only the first part of the season, pre-All Star Break. The Mariners have been through so much together as a team that, at times, it feels they've already played a full season plus.

And now, they face their latest challenge.

It seems as if, all season, we've pointed to the next big game, or big series, as a determining factor in whether the Mariners can continue to advance against odds and hope.

And in a sense, that's what it has been.

For the Mariners, it really has been a game-to-game, series-to-series approach. And the successes they've had up until now, like continued success on a roulette wheel, have enabled them to keep on playing games that matter.

Without a huge win by Felix Hernandez over Tampa Bay back in April, the Mariners probably tumble out of first place a little quicker than they did and maybe are not as close to the Texas Rangers as they are right now.

More recently, two wins in Anaheim in late May helped them overcome the disaster of a blown 8-1 lead in the series finale.

And then, in June, taking seven of nine from the Padres and Diamondbacks gave them that push needed to cross the .500 barrier and avoid falling six or seven games out of first place. Bought them some time to get things right.

Then came the nine-game road trip, when the season really did hang in the balance.

They went 5-4, again putting off a tumble into irrelevancy.

And now, after dropping two games they shouldn't have to the Orioles, the Mariners -- with new addition Chris Shelton up from Tacoma -- find themselves in another of those key situations where they have to win to keep on playing and avoid a trade deadline sell-off.

The stakes here are pretty clear.

Drop three of four and the M's are 6 1/2 games out and deadline sellers heading into the second half.

Split this series and they're 4 1/2 back and really, if you're the team's management, you've got your finger on the "sell" button every night.

Take three of four and the M's are probably no worse than three games out.

So, it's pretty clear. This really is -- once again -- do or die. And so far, in all the these key tests, the Mariners have been the doers.

It all starts tonight, with a game that truly is key to the series. The M's have the guy they want, Hernandez, on the mound. Lose this game, they put themselves in position of really having to sweep the weekend just to stay reasonably close. Not a spot any team wants to be in. Having to take three of four isn't really where they want to be either. But that's what blowing a 3-0 lead in the ninth to a last-place team can leave you with.

The M's are very close to a "buyers or sellers" decision here. These games, each and every one, are critical. That's what makes it so fun.