Rather than being assured of a job, incumbent Cristhian Martinez is among four relievers competing for one and possibly two spots in the Braves’ bullpen, manager Fredi Gonzalez said Thursday.

It had been assumed that Martinez was a lock because Gonzalez and Braves officials never indicated the team’s incumbent long reliever might not be one.

Gonzalez named sidearmer Cory Gearrin among six penciled in for spots with Craig Kimbrel, lefties Eric O’Flaherty, Luis Avilan and Jonny Venters, and offseason addition Jordan Walden, provided Walden can get ready in time after missing much of the spring with a bulging disc.

Gonzalez also gave a vague update when asked why Venters hadn’t pitched in a week since a four-walk inning against the Cardinals. He said the Braves decided to “back off” Venters a bit, but when asked if the lefty was hurt or tired, Gonzalez said no. He said Venters should be ready for the season.

Venters has thrown at least one bullpen mound session this week and said he felt good. The lefty said he was healthy and that the Braves rested him a while because it was a long spring.

Gonzalez named Martinez, Anthony Varvaro, David Carpenter and Wirfin Obispo as candidates for the open spot, or two spots if Walden isn’t ready. Gonzalez said Walden would make four more appearances before a decision is made.

Varvaro and Martinez are out of minor-league options, which probably makes them favorites because they couldn’t be sent to the minors without going through waivers.

Martinez pitched 151 1/3 relief innings in 100 appearances the past two seasons for the Braves and had a 3.91 ERA in 2012.

“I don’t think there’s any better long guy in baseball than Christian Martinez,” Gonzalez said.

Martinez has pitched seven times and given up three runs in three of those appearances. Some red flags might have gone up when he gave up five hits and three runs in three innings Monday in a minor-league game against Double-A Erie.

Still bunched: The third-base competition has been too close to call, so Juan Francisco and Chris Johnson likely will start out as a platoon, with Johnson also serving as backup first baseman.

“Both of those guys are playing such great baseball right now,” Gonzalez said, “so it would be unfair to say, you’re the starter.”

Before Thursday, Francisco was hitting .353 (18-for-51) with five home runs, 11 RBIs and a .686 slugging percentage, and Johnson was at .352 (19-for-54) with three homers, 11 RBIs and .537 slugging.

J-Up's blast: If spring training is any indication, new left fielder Justin Upton is going to give Braves fans plenty of thrills. He belted a homer over the 60-foot tall scoreboard in left-center field Thursday night in a 4-3 win against Washington at Champion Stadium, snapping Dan Haren's streak of 10 consecutive batters retired.

Upton has three homers in three games and has hit .286 with five homers and a team-high 17 RBIs in 56 at-bats.

Earlier this spring he hit what many observers believed to have been the longest homer to left field since the ballpark opened, clearing the grass berm and a fence behind it. Thursday’s homer appeared to travel at least 460 feet.

Hudson knuckler: Tim Hudson threw a knuckleball to Adam LaRoche in the second inning, after his friend and former Braves teammate dared him to.

“He’s thrown me a knuckleball (before); that was the second time,” LaRoche said. “Another time he went to switch balls and threw one right at my head, and it went all the way to the backstop. He just likes having fun. That was funny.

“I actually gave him the knuckleball signal walking up. I didn’t think he would. I should’ve known better.”

Hudson had his best night of the spring, allowing six hits and no walks with five strikeouts in six scoreless innings. He threw 45 strikes in 65 pitches, including the knuckleball to LaRoche for a ball.

“It’s a new pitch I’ve been working on,” Hudson deadpanned. “I was going to wait till the All-Star break to break it out, but it’s been so good lately that I’m going to start implementing it.”