HOUSTON -- The juxtaposition was stark on March 19 in Port St. Lucie, Fla., when the Astros, who had gone more than three weeks without winning a game against Major League competition, kicked the ball around Tradition Field against the Mets and lost, 12-1, in a Spring Training game that was all but over in the second inning.

Houston was headed nowhere; the Mets, everywhere. But how things change.

It is the Astros now that are beaming, the Mets who are too shocked even to be steaming. And the Mets' sixth loss in eight games Friday, a 5-4 defeat to a suddenly contending Astros team, served as little more than a reminder of how quickly baseball fortunes can reverse.

"That's kind of the difference in a team that's playing good and hot, and a team that's not playing so well," Mets manager Jerry Manuel said of the proceedings.

The impact of such sudden reversals of fortune was not lost on Jeff Francoeur, whose trade from the Braves to the Mets now has him looking up. Yet Francoeur was gazing in another direction in the seventh inning Friday at Minute Maid Park, when Daniel Murphy sent what third-base coach Razor Shines thought might be a game-tying single into shallow right field.

As Francoeur was rounding third base on Shines' command, Astros right fielder Hunter Pence was transferring the ball from his glove to his right hand, preparing to unleash a throw home. And it was a bullet, though slightly up the third-base line and toward the infield side of the plate.

Francoeur set a path for the right side of the plate, away from Astros catcher Ivan Rodriguez. But Rodriguez shadowed him, forcing Francoeur to curve his route to the left.

What resulted was an awkward tumble to the plate that wasn't entirely a slide, and wasn't entirely a collision. Either way, Francoeur was out, and the Mets' most promising threat was over.

"I didn't have anything behind it," Francoeur said. "I probably looked like a pansy compared to the football mentality, but I could never square him up. Pence did what he does. He's got a great arm and he put a one-hopper right on the plate. I never had a shot."

But the Mets did have a shot, despite one of the worst outings of Johan Santana's season. Putting two more runners on base in the eighth inning did them no good, before they went quietly against closer Jose Valverde -- whom Francoeur felt was "toying" with the Mets by recording three outs without throwing a fastball -- in the ninth.

The Mets, of course, are reeling too much at this point to worry about the methods. Outcomes are all that matter, and Santana's was not pretty.

Only once before had Santana -- such a conspicuous bright spot heading into the night -- allowed a dozen hits in a game, during an equally maddening night last year against the Braves.

Despite some early hiccups, though, Santana seemed as if he had settled into Friday's game by the fourth, when he recorded two quick outs on seven pitches. But the next batter, Jeff Keppinger, saw 10 pitches before he launched a deep fly ball toward the short and quirky left-field wall, where Fernando Tatis stabbed his glove in the air without much chance to catch it.

Back on the mound, Santana regrouped and fired a first-pitch changeup right down the middle to Astros starter Mike Hampton, one of the finest-hitting pitchers in the history of the game. And Hampton, to the surprise of perhaps no one but himself, launched it into the left-field stands.

It was a turning point for Santana, who coughed up two more runs in the fifth inning. And it was a turning point for the Mets, who never led again.

"He's been doing that throughout his whole career," Santana said. "It's all about putting a good swing on it, and he did."

"And the short porch helped, too," Hampton acknowledged.

Hampton, for his part, held the Mets largely in check, allowing scattered RBI hits to Francoeur, Luis Castillo and David Wright and a home run to Omir Santos, but remaining in control against his former team.

And so here are the Mets, continuing in this inexplicable season, unable to beat a streaking Astros club that is now in contention both in the NL Central and Wild Card races. Losing to such a team is no sin. But the Mets need a reversal and they need it fast -- and if they can't spark one with their ace on the mound, then they can't help but wonder when they might spark one at all.

Their only optimism now has roots in the opposing dugout. The Astros -- that troubled, bedraggled bunch from Port St. Lucie -- is proof that fortunes can change in an instant.

Unfortunately, the Mets are running out of instants to spare.