ARLINGTON, Texas -- Max Scherzer couldn't wait to finally get back on the mound for the Texas Rangers. The three-time Cy Young Award winner also knew when he had done enough in his season debut.

Scherzer retired the first 13 batters he faced, and 15 of 16 overall, over five scoreless innings in the Rangers' 4-0 win Sunday over the Kansas City Royals.

"Everything from a baseball standpoint was telling me to go back out there. You know, I'm pitching well, I'm throwing the ball well," Scherzer said. "I just don't know how I'm going to recover from this. ... I was feeling my forearm kind of fatigued."

The 39-year-old Scherzer hadn't started a game for the Rangers since Game 3 of the World Series on Oct. 30, when he exited after three scoreless innings because of back tightness. He had surgery in mid-December to repair a herniated disk in his lower back, then during his rehab dealt with a nerve issue that was diagnosed and still an issue after he experienced right thumb soreness.

The only Royals batter to reach against him was MJ Melendez, who had a ground-rule double with one out in the fifth. Scherzer struck out four without a walk while throwing 39 of his 57 pitches for strikes.

His fourth and final strikeout Sunday was the 3,371st in his career to match Hall of Fame pitcher Greg Maddux for 11th on MLB's career list -- the four-time Cy Young winner who is the brother of the Texas pitching coach. Scherzer is second among active pitchers, with his strikeouts, 215 wins and 449 starts trailing Justin Verlander in each of those categories.

"I'll be honest, we weren't sure exactly where he was. ... It just makes you appreciate how good this man is," manager Bruce Bochy said.

"It shows the true veteran he is," Texas shortstop Corey Seager said. "Just all around a really good outing, big morale boost for our whole team."

Reigning champion Texas (37-40) already had a 3-0 lead when José Ureña replaced him on the mound to start the sixth inning, and finished off the team's second consecutive shutout win.

Scherzer, who turns 40 on July 27, needed only 27 pitches to get through the first three innings. He then had back-to-back 15-pitch innings before coming out of the game after a conversation in the dugout with Bochy and pitching coach Mike Maddux.

"There's a notion out there that I always fight to stay in ballgames, and there's some pretty good clips of me doing that," Scherzer said. "There's probably 20 other times where I'm actually telling the manager I'm coming out, I need to come out of the ballgame. ... I'm very aware of my arm. I'm very aware of where I'm at, and what I can and can't do. I know you're going to introduce more risk if I continue to go back out there. And so, you know, we have to minimize risk at this point."

After the deadline trade last summer that sent him from the New York Mets to Texas, Scherzer was 4-2 with a 3.20 ERA in eight regular-season starts for the Rangers before being sidelined by a shoulder muscle strain. He returned to make two starts in the AL Championship Series, then made his World Series appearance.

It was Scherzer's first regular-season start since Sept. 12, when he threw 5 scoreless innings at Toronto.

Scherzer struck out 17 over 11 innings and had a 4.91 ERA in three rehab starts for Triple-A Round Rock. The first was April 24, but he was then sidelined by the nerve issue until the other two June 9 and 15.

"It was just fun to get back out there and compete," he said. "Be on the mound, and being in sync with the game, with the flow of the game."

The Associated Press contributed to this story.