Bruce Chen (back) will make a minor league rehab start Tuesday will Double-A Northwest Arkansas.

Chen, out since late April with a bulging disk in his lower back, is scheduled to throw 45 pitches. He figures to return in the next couple of weeks, but he might do so in the bullpen.

Bruce Chen (back) will be cleared for a rehab assignment if he gets through a bullpen session Sunday with no issues.

Chen has already thrown a simulated game and live batting practice this week. It's not clear how many rehab starts he'll need, but he's close to returning. However, it could be as a reliever.

Bruce Chen (back) threw live batting practice on Friday.

It comes after he had a successful simulated game on Monday. Chen is nearing a rehab assignment and should be ready to rejoin the Royals in early June. As long as Yordano Ventura (elbow) can avoid the DL as the Royals expect, Chen might return as a reliever.

Bruce Chen (back) felt "really good" during a 25-pitch simulated game Monday.

"It felt good," Chen said. "Really good. The last three days, it really got better, significantly better." The Royals haven't decided when Chen might begin a rehab assignment, but it should be soon. With Danny Duffy pitching well, Chen might return as a reliever.

Bruce Chen (back) isn't close to beginning a rehab assignment.

Chen, who is nursing a bulging disk in lower back, threw a more intense bullpen session Saturday, but he's still got a ways to go. "I don't imagine it's going to be in the next four, five, six, seven days" that he takes a mound in a minor-league game, Royals manager Ned Yost said. With Danny Duffy pitching well, Chen might not have a rotation spot waiting for him once he's ready.

Bruce Chen (back) hopes to throw a light bullpen session Wednesday.

Nursing a bulging disk in lower back, Chen has been limited to playing catch to this point. There's no timetable for the veteran left-hander's return to the Royals' rotation, but he does appear to finally be making some progress.

Royals general manager Dayton Moore said Tuesday that the club is "unsure" about Bruce Chen's (back) timeline at this point.

The Royals had been hoping he was ready on May 17, when they next need a fifth starter after Thursday, but that appears to be up in the air. "We're still unsure about Bruce's timeline at this point," Moore said. "He's not throwing a baseball competitively right now. And every day a pitcher doesn't, it gets to a point in time where you've got to build him back up. And those things take time."

Royals placed LHP Bruce Chen on the 15-day disabled list, retroactive to April 25, with an inflamed disk in his back.

Chen received an epidural for his back on Tuesday but didn't experience the necessary improvement to avoid a trip to the DL. It's not clear at this point how long he'll be sidelined Danny Duffy is expected to take Chen's place in the rotation.

Royals manager Ned Yost said Thursday that he expects Bruce Chen (back) to be placed on the disabled list.

Chen received an epidural Tuesday for an inflamed disk in his back and apparently didn't feel any better during a bullpen session on Thursday. Danny Duffy is likely to start in his place Saturday against the Tigers, though he's likely only good for around 65-70 pitches.

Bruce Chen was given an epidural Tuesday for the inflamed disk in his back.

Chen might not be able to make his scheduled start Saturday against the Tigers. The 36-year-old left-hander has posted an ugly 7.45 ERA and 1.81 WHIP this season.

The Royals are skipping Bruce Chen's spot in the starting rotation.

The Royals are able to do so after Monday's scheduled off-day. Jason Vargas, Yordano Ventura, and Jeremy Guthrie will pitch against the Blue Jays this week.

Bruce Chen was tagged for five runs in 4 1/3 innings Thursday in a loss to the Indians.

Chen has allowed 15 runs over 13 innings in his last three starts. It's not going to lead to him losing his rotation spot right now -- with Danny Duffy kicking butt in the bullpen rather than knocking down the door in Triple-A, there's no one to step in -- but he probably won't get as much rope as he would if he threw 94 mph rather than 84 mph. Toronto is up next on his schedule.

Bruce Chen notched his first win of the year despite allowing four runs over five innings Saturday against the Twins.

It's strange to write it, but as well as the Twins have been swinging the bats, allowing four runs in five innings isn't bad. Chen missed his previous turn with a tight left glute muscle, so he was making his third start of the year today. He'll pitch in Cleveland next time out.

Bruce Chen has been scratched from his scheduled start Thursday due to a tight left glute muscle.

Chen said he's been dealing with the tweaked glute for about a week, which might explain the Twins getting to him for six runs in 3 2/3 innings his last time out. James Shields' start was bumped up to Thursday to accommodate, and the hope is that Chen will be ready to start Saturday's game -- a rematch with those Twins -- instead.

Bruce Chen was lit up for nine runs -- eight earned -- over four frames against the Mariners Tuesday.

He gave up a whopping 11 hits -- including a pair that went over the fence -- while walking two. Chen entered Tuesday with a solid 4.05 ERA during Cactus League play and had walked just one hitter, so we shouldn't read too much into one ghastly performance. He'll be the Royals' No. 4 starter this season.

Bruce Chen surrendered three runs in 5 1/3 innings of work in Thursday's start against the Angels.

Chen gave up two home runs: a solo shot to Albert Pujols in the first inning, and a two-run blast to Mike Trout in the sixth. Overall, Chen allowed six hits, walked none, and struck out one. The homers were the first Chen has allowed in the Cactus League, as he has otherwise pitched well this spring.

Bruce Chen was his typical self in Sunday's Cactus League loss to the Rockies, surrendering two runs on four hits over his three innings of work.

The veteran left-hander walked one and struck out two on the day. The Rockies jumped on him to push two runs across in the first inning with three consecutive hits, but he settled in nicely afterwards. Unless he has impeccable command in a given start, his underwhelming stuff make him likely to post horrifying ratios, and his inability to generate strike outs make him a terrible fantasy option in all formats.

Bruce Chen pitched three perfect innings against the Reds on Tuesday.

Chen struck out three as well. The 36-year-old lefty will return to the Royals' rotation after posting a 3.27 ERA between 15 starts and 19 relief appearances last season. Chen has been solid in two out of the last three seasons, but his peripherals and age make him a scary gamble in mixed leagues.

Blair Kerkhoff of the Kansas City Star reports that Bruce Chen is all but assured of a spot in the Royals Opening Day rotation.

That would leave Danny Duffy, Yordano Ventura, Kyle Zimmer and a host others who are more talented to compete for the final spot in the Royals rotation. While Chen's ERA and WHIP make his 2013 season look strong, his 4.93 xFIP, .255 BABIP against and miniscule strikeout rate paint a much different picture. He should be avoided in all fantasy formats.

FOX Sports' Ken Rosenthal reports that the Royals have re-signed left-hander Bruce Chen.