Nate McLouth grounded Darvish's first pitch toward first baseman Michael Young. The longest-tenured Rangers player got charged with an error when he tried to backhand the ball, which ricocheted off the heel of his glove and away from him.
McLouth stole second base on the third pitch. J.J. Hardy then drove him in by grounding a hard single up the middle — the Orioles had only one more hit until a sequence in the sixth that needed some interpretation.
The O's had consecutive singles to start the sixth before Jones' sacrifice fly made it 2-1.
After backing up the plate when Jones hit the ball in the air, Darvish started stretching his shoulder and rolling his neck. Washington and pitching coach Mike Maddux went out to the mound to try to figure out what was wrong when their pitcher still looked uncomfortable.
Darvish's translator, Joe Furukawa, was also on his way out before initially being waved back by umpires. The six umpires then conferred before allowing the translator to come out while Darvish kept stretching and then threw a couple of pitches. Darvish said he had a cramp in the muscle on the top of his shoulder.
Darvish finished the sixth with a strikeout, and started the seventh with another, before Ryan Flaherty's single and a sac bunt by Manny Machado. Derek Holland took over and gave up an RBI single by McLouth for a 3-1 lead.
Even though he was a rookie in the majors, the 26-year-old Darvish was 8-2 with a 1.38 ERA and five complete games in 11 postseason starts for the Hokkaido Nippon-Ham Fighters from 2006-11.
McLouth added a sacrifice fly in the ninth, when the Orioles scored twice against Rangers closer Joe Nathan.
Jim Johnson, who set an Orioles record with 51 saves, allowed a walk and two hits, including a two-out pinch single by 19-year-old Jurickson Profar, before Murphy's game-ending flyball to left.
Saunders, who was with Arizona until the end of August, benefited from three double-play grounders and some bad swings by slugger Josh Hamilton, the former AL MVP and free-agent-to-be who might have played his last home game in a Texas uniform.
Hamilton was 0 for 4 with two strikeouts, both on three pitches. He swung at the first pitch his other at-bats — grounding in a double play in the first that did send home Texas' only run and hit a comebacker for the final out in the eight with a runner at second base.
Even if a second wild card hadn't been added this year, the Orioles and Rangers would have been playing a winner-take-all game since both had 93 wins in the regular season.
Under the old playoff rules, they would have met in a 163rd regular-season game the next day to determine the only wild card, with the winner hitting the road to open the division series.
With the new format, it was a postseason game after an extra day — when Washington gave his team off after being swept in Oakland and losing the AL West crown on the regular season's final day.
The new rules also eliminated the prohibition against teams from the same division meeting in the ALDS, setting up the Orioles and Yankees.
For the Rangers, they're headed into their longest offseason in three years.
NOTES: Orioles 1B Mark Reynolds got hit on his right hand by a pitch in the second. He then stole second, matching his stolen base total from the regular season before getting stranded there. ... The ceremonial first pitch was thrown by 86-year-old Sister Frances Evans, a longtime Rangers fan who was escorted by Nolan Ryan to a spot a few feet in front of the plate. She wound up and threw to former Rangers catcher Jim Sundberg.