Williams pitched six solid innings in an unlikely start and Feliz got his first save in three seasons for the Rangers in a 4-1 victory over AL West-leading Oakland on Friday night.
"I'm happy to be back in the role, and the more happy I feel because I got a win for the team," Feliz said through an interpreter after working around two runners in a scoreless ninth. "I like to have that adrenaline flow through me, because I feel fans pulling for me to finish."
Feliz, the closer again after Joakim Soria was traded to Detroit earlier this week, got his first regular-season save since 2011. The former All-Star's last opportunity, before moving to the rotation and then getting hurt and needing Tommy John surgery, was a blown save in Game 6 of the 2011 World Series against St. Louis.
"He got it done. I'm more than certain the more he gets the ball, the easier it will probably come," manager Ron Washington said. "We'll just keep giving him the ball and see where it goes."
Elvis Andrus had a triple among his two hits and scored twice for the Rangers, who had lost their seven previous home games in July and were coming off a 2-5 road trip out of the All-Star break.
The Athletics still have the best record in the majors at 63-39, and they have a 22 1-2-game division lead over last-place Texas, which has won only six of its last 33 games.
Williams (2-4) allowed one run while striking out four without a walk. The 32-year-old right-hander was released by Houston earlier this month and signed to a minor league deal with the Rangers two weeks ago. He also pitched previously for San Francisco, the Chicago Cubs, Washington and the division rival Los Angeles Angels.
"I didn't think I was going to come to Texas because I played for the rival," Williams said. "I can't really look at the future right now. I can only look at the present."
Texas purchased Williams' contract from Triple-A Round Rock as planned Friday to start in place of Nick Tepesch, who pitched in relief in the Rangers' 14-inning loss to the New York Yankees on Tuesday night. Tepesch is scheduled to start Saturday night.
The Rangers have used a majors-high 52 players, three short of the club record. But 31 pitchers broke the previous mark, and they still have reliever Nate Adcock waiting for his season debut after coming up from Round Rock on Thursday.
Texas led for good on J.P. Arencibia's RBI single after Jim Adduci had a leadoff double over center fielder Yoenis Cespedes in the second off Jason Hammel (0-3). Andrus had a two-out triple in the third past Cespedes and scored on a single by Alex Rios.
Hammel lost his third straight start since coming from the Chicago Cubs with Jeff Samardzija in the July 5 trade. Hammel allowed four runs (three earned) in 5 2/3 innings.
"The easiest thing here is to start getting down on myself, but I'm not going to do that," he said. "I did a lot of good things tonight, save for a few hard-hit balls."
Yoenis Cespedes was back in Oakland's lineup after missing Thursday with a sprained right thumb, and started in center field for only the second time this year. He had an RBI single in the sixth for Oakland's only run.
Cespedes had an error in the sixth on a wide throw home after Adrian Beltre's RBI single. Rios and Beltre got an extra base, and Adduci followed with a sacrifice fly.
Oakland manager Bob Melvin successfully challenged to have two safe calls at first base overturned on replay. Arencibia was initially ruled safe on a pickoff throw by Hammel in the fourth. Andrus was called safe on what would have been an infield single, but wound up the inning-ending out in the seventh. ... Rangers pitching coach Mike Maddux and longtime broadcaster Eric Nadel have hall passes to miss this weekend's series. Nadel, in his 20th season as the lead voice on Rangers radio broadcasts, will receive the 38th Ford C. Frick Award at the annual Hall of Fame awards ceremony Saturday in Cooperstown. Maddux is there for the National Baseball Hall of Fame induction Sunday of his brother Greg, a special assistant for the Rangers.