Rapid Reaction: Nats 9, Mets 7 (10)

NEW YORK -- Still 90 wins to go.

Jeurys Familia surrendered a tiebreaking sacrifice fly to Ian Desmond after allowing two singles and having the runners advance on Travis d'Arnaud's passed ball, and John Lannan subsequently surrendered a three-run homer to Anthony Rendon in his first career major league relief appearance as the Washington Nationals rallied to beat the Mets 9-7 in 10 innings before an announced Opening Day crowd of 42,442. Lannan, whose previous 148 appearances had been as a starting pitcher (and mostly with the Nats), had walked the lefty-hitting Adam LaRoche to bring up Rendon.

Trailing 9-5 in the bottom of the 10th, David Wright produced a two-out, two-run homer.

Bobby Parnell, in his first game since last July 30, surrendered a game-tying RBI double to Denard Span with two outs in the ninth as the Nats pulled even at 5. Parnell was returning from surgery to repair a herniated disk in his neck.

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Juan Lagares had staked the Mets to a one-run lead in the bottom of the eighth with a homer.

Known for his defense, not his bat, Juan Lagares nonetheless had given the Mets a 5-4 lead a half-inning earlier. Lagares homered against Tyler Clippard to begin the eighth -- the Mets’ first hit in five innings.

The Mets' MLB-best Opening Day winning percentage slipped to .642 (34-19). Their batters struck out 17 times.

Gee sharp: Making his first career Opening Day start, Dillon Gee surrendered a mammoth two-run homer to LaRoche in the second inning, then bulldozed his way through the Nats' lineup in the middle innings. Gee retired the next 15 batters, until Bryce Harper singled off the glove of Eric Young Jr. at second base with one out in the seventh.

Gee stumbled that frame while trying to protect a 4-2 lead.

After E.Y. Jr. could not turn a double play on a grounder to shortstop, which swapped Desmond for Harper on the basepaths, Gee walked LaRoche. Gee then surrendered a two-out, run-scoring double to Rendon as Washington pulled within a run.

The relief corps did not help.

Terry Collins summoned Carlos Torres with two in scoring position and Gee’s pitch count at 100. Torres walked pinch-hitter Nate McLouth on four pitches to load the bases.

Collins returned to the mound and called for Scott Rice to face Span. Rice walked Span on four pitches to force in the tying run.

Jose Valverde, the fourth pitcher in four batters, finally bailed out the Mets in his debut with the organization. Valverde, the primary setup man, struck out Ryan Zimmerman with the count full to leave three Nats on base and limit the damage to a 4-all tie.

Valverde also contributed a perfect eighth. It marked his first scoreless appearance of more than one inning since June 28, 2010, with the Detroit Tigers. Valverde struck out three of the four batters he faced.

Gee’s final line: 6.2 IP, 4 H, 4 R, 4 ER, 2 BB, 5 K, 1 HR.

Gee had produced a 4-2 record and 2.72 ERA in six starts against the Nats last season.

Brown delivers: Andrew Brown made his first Opening Day roster arguably because the Mets are carrying an extra bench player while Jonathon Niese is on the DL.

Brown also found his way into the starting lineup because of a trio of circumstances:

Chris Young has a right quadriceps strain.

Daniel Murphy is away for the birth of his first child, requiring E.Y. Jr. to shift to second base.

• Collins did not feel comfortable playing Lucas Duda in the outfield after Duda missed more than two weeks of spring training with a hamstring injury.

So what did Brown do? Of course, he belted a three-run homer against Stephen Strasburg in his first at-bat. The first-inning blast staked the Mets to a 3-0 lead. Brown became the first Met to homer in his first at-bat of a season since David Wright against the Marlins’ Josh Johnson on Opening Day 2010.

Meanwhile, Strasburg settled down and allowed four runs on five hits and two walks while striking out 10 in six innings. He retired the final 10 batters. The strikeout total was the most ever against the Mets on Opening Day, topping nine apiece by Curt Schilling (1998), Steve Carlton (1983), Steve Blass (1970) and Don Drysdale (1965).

Ouch: Harper was kneed in the right side of the head by E.Y. Jr. while Harper was sliding into second base in the second inning breaking up a double play. Harper’s helmet went flying and he was escorted off the field by a trainer, but did remain in the game.

Debutant: Curtis Granderson went 0-for-5 with three strikeouts in his Mets debut.

MIA: The Mets took the field for the top of the first without a first baseman. Collins then went to the plate umpire. And, after a brief delay, Ike Davis took first base. Davis finished 0-for-2 with a walk before departing on a seventh-inning double-switch during which Duda entered.

It’s a start: Ruben Tejada, the shortstop essentially by default, singled in his first at-bat of the season. He finished 1-for-4.

What’s next: After an off day, the Mets continue their series against the Nats on Wednesday at Citi Field at 7:10 p.m. Bartolo Colon (18-6, 2.65 ERA in 2013) makes his Mets debut opposite left-hander Gio Gonzalez (11-8, 3.36).

The Mets say Murphy and Chris Young both should be in the lineup. Righty-hitting Josh Satin is expected to start at first base against the southpaw Gonzalez.