We are reaching September, and with it comes the question: Who is the most important player for the Red Sox the rest of the way?

You can make a great case for Koji Uehara.

There’s no bigger issue on this team right now than the bullpen. It’s amazing to think the Red Sox’ fate is so tied into two players 40 or older — David Ortiz and Uehara — but it is.

When Uehara hurt his pectoral muscle in mid ­July, the Red Sox lost their eighth-inning reliever and their bullpen was turned upside-down. He may be 41 years old and prone to injury, but he’s also ­effective and someone you trust to pitch the eighth. Oh, he’s had a few missteps, but before he was injured, he had saved four straight games in Craig Kimbrel’s absence.

Uehara also needs a strong comeback for his own future employment. He’d like to keep pitching. The chances of him getting another $9 million deal appear slim, though a strong finish might give the Red Sox pause about letting him become a free agent.

Let’s face it, the relievers leading up to Kimbrel have been a disaster since Uehara went down. Jun­ichi Tazawa, Matt Barnes, and Brad Ziegler have been erratic at best. Robbie Ross Jr. has been the most consistent. And Fernando Abad has not lived up to the hype from his first half with last-place Minnesota.

A strong Uehara will give the Red Sox a legitimate chance to lock up games . So often recently, they have been losing games they’ve led from the sixth inning on, as a result of bullpen implosions. An effective Uehara ends that.

The question is, when will Uehara be activated? And is he ready to be that impact pitcher again?

The Red Sox are surprised that Uehara is so far ahead of schedule and that he feels his stint on the disabled list should end this weekend in Oakland.

They have kicked the tires on a bunch of relievers who cleared waivers. It appears that Joakim Soria is no longer available as the Royals need him in their push to make the playoffs. The Red Sox reached out to Jonathan Papelbon, their former closer, but he has yet to decide where he’ll pitch, if anywhere at all.

But a healthy Uehara would be the best move of all.

He is scheduled for a bullpen session Wednesday and then will face hitters Saturday in Oakland. If all goes well, he could be activated.

Manager John Farrell has pointed out that Uehara doesn’t need a lot of game action to be ready, as evidenced by his limited work in spring training. And there is not a lot of time left on the minor league schedule to get him into games there.

Uehara said it was more of a mental hurdle than a physical hurdle as he attempts to regain his effectiveness.

You can see why Farrell is eager to get his eighth-inning man back as soon as possible.

“Honestly, he has a chance to make a very positive impact once he does return,’’ Farrell said.

If Uehara can come back, the Red Sox would use Clay Buch­holz late in games. They also plan on bringing Joe Kelly into the mix, and that may slot Barnes lower on the totem pole.

Uehara has not been the same pitcher since injuries undercut his career. But when he’s in a good stretch, his split-fingered pitch and 88-mile-per-hour fastball can be very effective.

He also hasn’t minded becoming the set-up guy after being the closer who helped the Red Sox win the 2013 World ­Series.

For all the relievers the Red Sox could add, waiting for ­Uehara might be the best decision they could make. You’re not going to find anyone this good. You’re not going to find a reliever who has cleared waivers and doesn’t have large contract obligations.

With Uehara, Tazawa, and Ziegler becoming free agents at the end of the season, the Red Sox will have the means and the money to rebuild their bullpen. But right now, a blast from the past would suit them just fine.

Nick Cafardo can be reached at cafardo@globe.com. Follow him on Twitter @nickcafardo.