The last time the Red Sox and Yankees met nearly a month ago, tempers flared, a fight broke out and one of the best and oldest rivalries in baseball was back with a vengeance.
Of course, that's not to say the competitive spirit between the two teams ever goes away. But the rivalry is even better when both teams are dominating, and in that respect, the timing of the upcoming series at Yankee Stadium, which begins tonight, could not be better.
The Red Sox are 25-9, a game up in the American League East. The Yankees are 24-10, in second place, and on their best run in 20 years. Today will mark the first time the Red Sox and Yanks will play each other with the two best records in baseball since June 2, 2002. According to Elias Sports, Boston entered that game at 36-16, with New York at 37-19.
Our Power Rankings reflect the Sox and Yankees residing at the very top, with a newcomer sneaking into the top five.
Biggest jump: The Nationals improved nine spots, from No. 17 to No. 8. They had a good week, sweeping a four-game set with the Pirates and taking two of three from the Phillies. The Nats are back over .500 and looking more like they were expected to when the season started. The Nationals, winners of seven of eight entering their 8-5 victory in San Diego on Monday night, received terrific starting pitching over those eight games. The rotation registered a 1.95 ERA, allowing 11 earned runs over 50 2/3 innings. No starter allowed more than three runs.
Biggest drop: The Pirates ended a poor week with a good series against the Brewers, taking two of three at Miller Park. Still, it's been a rough go for the Bucs of late. Since winning 11 of their first 15 games, they've lost 12 of 20 and, until their 9-0 win in Milwaukee on Sunday, were having trouble scoring runs. They dropped 10 spots in our rankings, from No. 7 to No. 17. This is more a reflection of where we see Pittsburgh settling as the season continues -- middle-of-the-pack and interesting, but not elite -- especially in a tough National League Central.
Also notable: The Mets dropped eight spots, from No. 6 to No. 14.
Power Rankings, Top 5
1. Red Sox (2 last week)
The Red Sox have won eight of 12 since their season-worst three-game losing streak a couple of weeks ago and began their current three-city, 10-game road trip on a high note, taking three of four from the Rangers. Over their past seven games, the bullpen threw 26 1/3 innings while posting a 2.73 ERA with 37 strikeouts.

2. Yankees (4)
It's not just that the Yanks have won 16 of 18. It's who they've beaten that makes this streak so impressive. It started with three wins in a four-game set with the Blue Jays and continued with a four-game sweep over the Twins, a three-game sweep of the Angels, three wins in four games with the Astros and a three-game sweep of the Indians. They outscored opponents 107-48. They've also played very well at home, stringing together a nine-game winning streak.

3. Astros (1)
Heading into their opener in Oakland on Monday night -- a 16-2 win over the A's -- the Astros had lost five of their previous six and had batted .229 with 17 runs scored across those six games. They just finished up a meatier part of their schedule that included series losses to two teams that are proving to be early-season powerhouses, in the Yankees and D-backs. The Astros may have a slight reprieve this week -- after the current set with the A's, they go home to host the last-place Rangers.

4. Diamondbacks (3)
Imagine this team when Paul Goldschmidt starts hitting again. The D-backs slugger and perennial NL MVP Award candidate is batting .225 on the season and is hitless in his past 23 at-bats, with 11 strikeouts. And yet, the D-backs will enter their series with the Dodgers today with a comfortable lead in the NL West. Center fielder A.J. Pollock has a lot to do with Arizona's success -- in his past 10 games, he's 15-for-37 (.405) with five homers and 12 RBIs.

5. Cardinals (11)
If the Cardinals could have scripted their weekend with the Cubs, they would have, of course, eliminated the part where they lose catcher Yadier Molina for a month, and they would have completed the sweep over their division rivals a little more efficiently. In back-to-back extra-inning, walk-off wins, the Cards' bullpen used nine relievers across 14 2/3 innings. Other than that, good times are rolling in St. Louis, where the Cardinals are off to a 12-6 start at Busch Stadium and are in first place in a tight NL Central division.

The rest of the Top 20
6. Angels (13 last week)
7. Cubs (5)
8. Nationals (17)
9. Indians (9)
10. Brewers (16)
11. Rockies (18)
12. Braves (8)
13. Blue Jays (12)
14. Mets (6)
15. Phillies (10)
16. Mariners (14)
17. Pirates (7)
18. Giants (20)
19. Dodgers (15)
20. Athletics (19)