John Isner, whose world ranking of No. 12 is the highest of any American on the ATP Tour, lost his opening match at the Citi Open on Wednesday night, then blasted tournament organizers for placing his match against Steve Johnson on a grandstand court.

“I didn’t like playing out there. I thought it was [expletive],” Isner said following his 6-7 (7-5), 6-3, 7-6 (8-6) loss to his fellow American. “I just didn’t think I deserved to play there. Simple as that.”

World No. 7 Milos Raonic and American Jack Sock played on Stadium Court at William H.G. FitzGerald Tennis Center at the same time as the Isner-Johnson match.

“At an international tennis event of this magnitude, many factors are at play in scheduling decisions, including domestic and international television and many more,” tournament director Jeff Newman said in a statement.

“As a player who has played so well here in the past, we can appreciate it’s a tough loss, but credit to Steve Johnson for the win.”

With the third-set tiebreaker at 6-6, the big-serving Isner uncharacteristically double faulted to give Johnson match point. Johnson held serve on the match point to knock out the Citi Open runner-up last year.

Johnson, ranked No. 68, shared some of Isner’s sentiments.

“I was surprised [to be on the grandstand court],” Johnson said. “. . . I thought it was a great atmosphere. Pretty intimate court, and people are right on you. I thought it was great.

“Of course I’m happy to have won, but I thought it was kind of a bummer because he deserves to be on a big stage, but I’m not in control of that.”

Johnson next will play Ivo Karlovic.

Hard courts suit Raonic

After his best results came on his worst surfaces, Canada’s Raonic was happy to play on his favored hard court, and it showed in a 7-6 (7-3), 7-6 (7-3) win over Sock.

“After spending four months of playing tennis and constantly adjusting to figure out the surface, I come to this and know how to play the surface,” Raonic said. “I don’t have to think about what I need to do for hard courts; I just have to think about hitting my shots well.”

Sock got the first service break of the match in the second set on a Raonic double fault and took a 5-3 advantage. He then got broken in the next game.

Sock and Raonic have played five times, with Raonic winning the past four meetings. They most recently played in Wimbledon, where Raonic also beat Sock in straight sets. . . .

Other top seeds in the Citi Open advanced Wednesday. Japan’s top player and the third seed in the tournament, Kei Nishikori, moved on with a win over American Sam Querrey, 6-4, 5-7, 6-4.

After not playing well in last summer’s hard-court season, Nishikori got off to a promising start. Querrey had a 3-1 record over Nishikori entering the match.

“This swing until the U.S. Open is very important,” Nishikori said. “I like hard court, and I’ve been playing well, and I have more confidence than before, so I want to do good here.”