Among the many reasons that this weekend’s Davis Cup final between America and Russia, in Portland, Ore., might one day be remembered as one of the competition’s finest moments, the most important is perhaps this one: There aren’t two more different teams — in terms of coaches, players, and personalities — on earth.

The American squad hasn’t changed in four years, which is not only a testament to the commitment of our country’s top players (and the lack of depth in America at the moment), but the strengths of Patrick McEnroe, the underrated captain of this team since 2001. McEnroe hasn’t had to make many decisions during his tenure, but the fact that he hasn’t is his greatest success. Andy Roddick, James Blake, and Bob and Mike Bryan are loyal to their easygoing captain. How many nations have players of this caliber who skip tournaments — and the dollars and ranking points that go with them — in order to stay healthy for Davis Cup, as Roddick and the Bryans did this fall? It’s fair to say that no American Davis Cup team has invested more in the cause. Roddick looks at the Davis Cup, which America hasn’t won since 1995, as a career-defining moment. Blake and the Bryans have followed his lead. McEnroe must receive credit for such enthusiasm. He’s the Terry Francona of tennis (yes, I’m from a state in Red Sox Nation, and I view Francona as a first-rate manager, not the lug he is often portrayed to be).

If McEnroe is the conservative, consistent leader who guides a potent team that lacks depth, his Russian counterpart, Shamil Tarpischev, is the ultimate gambler, largely because his inconsistent players force him to take risks. No team in the world has the depth of talent of the Russian squad. Yet, no team needs as much guidance and manipulation.

Since 2002, Tarpischev has masterfully steered his team to two Davis Cup titles, including last year’s. Along the way, his intuition has become legendary. In last year’s semifinal against the American squad in Russia, Tarpischev replaced a tired Mikhail Youzhny, who clinched the 2002 title, with the relatively untested Dmitry Tursunov on the final day of singles. Tursunov defeated Andy Roddick 17–15 in the fifth set, sealing the victory. In 2002, tied 2–2, he called on Youzhny, rather than Yevgeny Kafelnikov, to win the final match against France’s Paul-Henri Mathieu in France. Youzhny dropped the first two sets before winning in five.

The resolve of this American team and the unpredictable talent of the Russians make for a perfect contest. There’s no certainty here, save the Bryans, and even they might face a test from the team of Tursunov and Youzhny (right now, Igor Andreev and Nikolay Davydenko are the scheduled doubles team for Saturday, but that could change depending on Friday’s results). In singles, several dazzling (or dismal) performances by the Russians could determine things. McEnroe needs his players to stick to the script that has worked so well this year: one or two wins from Roddick and a win from the Bryans. Tarpischev, playing on the road with a slightly weaker team than he had last year, needs to make the best moves of his career. Many expected him to play Marat Safin, despite Tarpischev’s insistence that Safin, who has barely played since the U.S. Open, was in no position to help Russia (Safin will cheer from the sidelines). It wasn’t until yesterday afternoon that the Russians released their starting lineup — earlier in the week, Tarpischev said it was “too early.” When you have a match in four days and it’s still too early know what’s best for your team, that’s one strange team.

Here’s how the match-up looks so far, and I stress “so far,” since it would the Russians almost certainly will make a substitution or two before the weekend is out.

Andy Roddick vs. Dmitry Tursunov: These two have had some battles over the years, with Tursunov winning the most important of their five meetings in the Davis Cup semifinals last year. Both have big serves, but Roddick’s is the best on the tour. Tursunov has a lot more firepower from the baseline, but he’s often wild. All in all, though, this is about as perfect a situation as the Americans could hope for in the opener: their best player against someone he knows he can beat. If Roddick doesn’t win this one, things could get ugly, and quickly. But he should win.

James Blake vs. Mikhail Youzhny: Blake has been every bit as reliable as Roddick and the Bryans — reliably bad, that is. The 27-year-old American hasn’t played nearly as well this season as last season, and his performance in Davis Cup last year was, at best, so-so. He has a 3–2 record in singles this year, but two of those wins came in meaningless matches (the Americans had already clinched). Blake, like Roddick, has owned Nikolay Davydenko (6–0; Davydenko has won two sets total) and that’s why Tarpischev kept Davydenko out of singles for the first day (he’s 0–5 against Roddick). Blake and Youzhny have much in common: fearsome strokes, one-handed backhands, and pretty good hands at the net. There’s one big difference, though. Blake has not won a crucial match in his career, while Youzhny has shined in the Davis Cup (he’s choked elsewhere). If Blake and Roddick win, the Americans are a lock. The Russians are playing for a split.

Bob/Mike Bryan vs. Nikolay Davydenko/Igor Andreev: This looks like a surprising choice by Tarpischev, but consider it a placeholder. If both Tursunov and Youzhny lose on Friday, they might resurface to play the Bryans on Saturday. Or not. Davydenko has little experience in doubles, but he and Andreev did beat a good French pairing earlier this year, Sebastien Grosjean and Michael Llodra. If one of those teams somehow upsets the Bryans — and it would rank among the biggest upsets in Davis Cup history — Tarpischev might then try his luck with Davydenko and Andreev in singles. And of course, there’s always Safin.

Mr. Perrotta is a senior editor at Tennis magazine. He can be reached at tperrotta@nysun.com.