NEW YORK — Steven Matz's giddy grandfather popped out of his seat at Citi Field and shouted with unabashed glee. Boy, did he have plenty to cheer about.
In an astonishing and storybook debut, Matz became the only major league pitcher to drive in four runs in his first career game while leading the New York Mets to a 7-2 victory over the Cincinnati Reds on Sunday.
"Did it all today," Matz said.
Pitching about 50 miles from home with more than 130 family members and friends on hand, Matz got three hits and helped the Mets to a three-game sweep.
He was awfully impressive on the mound, too, working into the eighth inning after giving up a home run to his first batter.
"He was ready for this," Mets manager Terry Collins said. "All the things we heard from the guys in Triple-A, it was time. ... And today he showed it."
The club's latest prized pitching prospect, Matz had to wait 3 1/2 extra hours to make his much-anticipated debut because the teams needed 13 innings to first complete Saturday's game that was suspended by rain. Picking up in the seventh, New York won 2-1 with help from two miscues by Reds infielders.
Scores of fans, some already wearing Matz shirts and jerseys, came to see the lefty from Long Island pitch. But what really got the crowd going were his swings at the plate as the 24-year-old Matz, who grew up a Mets fan, rejuvenated an anemic lineup.
Matz (1-0) became the first player in franchise history — at any position! — to have four RBIs in his first major league game.
He did it with a two-run double off Josh Smith (0-1) over the center fielder's head in the second and a two-run single with the bases loaded in the sixth. In between those at-bats: Matz keyed a tiebreaking rally with another single, making him the first Mets pitcher to have hits in his first three at-bats.
He even slid hard into second to help break up a double play, helping New York tack on a run.
"I don't like being an easy out as a pitcher," Matz said.
No worries there.
By his turn in the fifth, fans had replaced the "Let's go Mets!" chant with "Let's go Matz!"
And with each successive hit, his family in attendance broke into delirious excitement — making his thrilled and animated grandpa an instant Internet sensation.
Matz's at-bats didn't only get fans, family and friends excited. The Mets were really desperate for a boost, too.
"That was a hit we needed, the entire team!" Collins said.
The Mets had scored just 15 runs in 10 games coming in, their worst string since September 1979, according to STATS. They have won four straight following a seven-game slide.
Curtis Granderson followed Matz's fifth-inning hit with an RBI double to make it 3-2. Matz's two-run single — followed by a big fist pump — in the sixth gave New York its most runs since June 14, when it scored 10.
Matz was just as good doing the job he's expected to do. A second-round pick in 2009, he had his career delayed by Tommy John surgery but has been stellar since at every level. Matz was even hitting over .300 at Triple-A Las Vegas.
In 7 2-3 innings Sunday, he allowed five hits and two runs, walking three and striking out six. Some fans booed when Collins came out to get Matz after 110 pitches.
After spending the night at his parents' house about an hour from Citi Field, Matz sat calmly at his locker before the resumption of Saturday's game. He had to stay out of the dugout until he was added to the roster as the 26th man for the regularly scheduled game.
Several dozen fans stood behind the bullpen and watched Matz warm up, taking pictures and videos with their phones through a chain-link fence.
Eagerly watching their buddy in the 'pen, too: budding aces Matt Harvey, Noah Syndergaard and Jacob deGrom. The fourth star pitcher the team has been promising fans to build a winner around, Zack Wheeler, is out after having Tommy John surgery.
"I think they have a great rotation," Reds second baseman Brandon Phillips said. "They have a lot of great guys over there and they pitched very well against us and you tip your hat when it's due."
Pumped up at the start, Matz threw a high 96 mph fastball for his first pitch to Phillips. The ball glanced off the catcher's mitt and practically sailed all the way to the backstop.
Matz fell behind 3-1, and Phillips drove the next pitch to deep left field for what was initially ruled a single off the wall. The call was overturned after a review of 59 seconds, giving Phillips a home run on his 34th birthday.
Phillips has hit safely in all 32 road games he's played against the Mets.
Matz settled in and didn't give up another hit until Todd Frazier connected for his 25th homer leading off the fourth to make it 2-all.
"He does what he does. He came right back at guys and attacked the strike zone," said catcher Johnny Monell, who caught Matz plenty with Las Vegas.
Mets: INF Daniel Murphy (strained left quadriceps) went 1 for 3 and played five innings at third base in a rehab game with Class A St. Lucie. He could be back with the Mets on Tuesday.
Reds: Mike Leake makes the second start of his career against Minnesota on Monday night. In 21 at-bats against the right-hander, the Twins have just one run and three hits — including a homer by Trevor Plouffe.
Mets: After an off day Monday, the Mets host the Cubs. Jonathon Niese has gone a career-high eight games without a win but he's pitched well in his last four starts.
AP Baseball Writer Mike Fitzpatrick contributed to this report.