The Yankees’ chances of gaining the division lead are infinitesimally small, but the three games against Boston, the first of which is today, are must-wins. Now eight games out of first place, the Yankees could sweep the six that remain with the Red Sox and still trail by two with very little season left. Their path to the postseason now lies through the wild card and Seattle, not Boston and the American League East. The wild card-leading Mariners have refused to let up, so every game from now on is as significant as a game with the Red Sox. Might as well start the winning habit with the real thing.

The Mariners have been surprisingly relentless. Since losing seven straight games in late July, Seattle has gone 19–9, a pace for 110 wins over a full season. They’ve averaged nearly six runs a game over that span, more than enough to outpace a mediocre pitching staff, which has allowed 4.88 runs per game over the same period. The Yankees must fight to keep pace, turning the pressure up on this series with Boston.

The 2007 edition of the Red Sox can hit, but the team doesn’t have a classic Boston bashing offense. The lineup has hit for good averages and is patient, but it isn’t sending an unusually high number of balls over the fences (the Red Sox rank ninth in the league in home runs). This is mainly due to three factors: Manny Ramirez’s off-year (although he’s still been plenty dangerous), J.D. Drew’s almost complete offensive collapse, and David Ortiz’s sore left shoulder, which hasn’t stopped him from having another great year, but seems to have held down his home run production.

The Yankees have the poor timing — typical for this season — of encountering Boston just as two of the three are heating up. Drew is batting .324 AVG/.400 OBA/.479 SLG in August and hit his first home run since June on Sunday. Ortiz is hitting .337/.454/.640 this month with six home runs, his most since April. Note that unless a move is made prior to tonight’s game, the Yankees will face Ortiz, whose power has been limited by left-handed pitchers to a greater extent than usual this year, with the not-ready-for-prime-time Sean Henn as their only lefty in the pen. Only Ramirez remains cold, batting .250 with one home run, hit 18 games ago, on the month.

The pitching match-ups may actually favor the Yankees. Tonight’s game pits Andy Pettitte against Daisuke Matsuzaka. Dice-K has more or less lived up to advanced billing, with a 3.76 ERA and 9.1 strikeouts per nine innings pitched, good for fourth in the league. Over the last month, Matsuzaka has pitched some of his best baseball of the season, posting a 2.97 ERA over six starts. A lack of run support has shackled him with the loss in three of those games, though only once, on August 15, did he fail to post a quality start. Pettitte’s last six starts have been even better, with the pitcher going 5–1 with a 2.36 ERA and just one home run. The game should be competitive.

Game 2 matches Josh Beckett with Roger Clemens. Beckett is trying to pitch his way to the Cy Young Award, with a 2.66 ERA over the last month. Not only is he striking out almost a man an inning, he’s walked less than two batters per nine innings pitched. Right-handed batters have barely touched him this season, with rates of .223/.249/.348. The Yankees have seen Beckett twice this season and handled him well, though, scoring nine runs in 13 innings.

The problem is not so much what Beckett might do to the Yankees, but their own horse for that night. At 44, Clemens is an amazing physical specimen. Very few pitchers have been able to pitch as well as he has at so advanced an age. The problem is that he can’t do it all the time. There have been games where he has been quite good, particularly in back-to-back starts in early July in which he allowed two runs over 16 innings. But there has been no game in which he’s resembled his old, dominating self. Just another pitcher now, Clemens is vulnerable to being pounded on an off-night, and he has been this season.

The final game has Boston’s own version of Clemens, Curt Schilling, taking the mound against Chien-Ming Wang. During Wang’s brief career, the Red Sox have had a good approach against Wang, using their patience to work him into favorable counts and then either walking or using his pitch-to-contact tendencies against him. Wang has pitched well against them at times, but he’s had only one dominating start against them in his career.

After missing six weeks with shoulder tendinitis, the 40-year-old Schilling is pitching well right now. Still, he’s a diminished pitcher. The former workhorse has made four starts since coming off the disabled list, pitching exactly six innings per game. His control remains exemplary — he’s walked just one in those 24 innings — but his velocity has ebbed, resulting in just 11 strikeouts. Being around the plate also means that a good number of balls are going out of the park.

It’s a shame that Clemens’s and Schillings’s schedules missed by just one day. A battle of diminished dinosaurs might have been a treat (or maybe just a depressing confirmation of the passage of time). But the Yankees can’t complain: Their weakest pitcher of the series, Clemens, will be going against Boston’s strongest, while they maintain good matchups in the two other games. In short, the Yankees could win two of three from the Red Sox. Simultaneously, the Mariners play the Angels and Indians. If the Yankees are going to catch a break, now is the moment — but they’ll have to earn it.

Mr. Goldman writes the Pinstriped Bible for yesnetwork.com and is the author of “Forging Genius,” a biography of Casey Stengel.