Lance Armstrong reportedly issued an emotional apology to several staff members at his Livestrong organization in Texas  ... amidst rumors that he's finally going to admit that he cheated.

According to the AP, Armstrong met with staffers right before he headed to an interview with Oprah Winfrey ... an interview in which he's rumored to finally admit he doped during his cycling career.

During the meeting with Livestrong staff, Armstrong reportedly choked up ... and said "I'm sorry" for letting everyone down.

Armstrong's apology was vague at best -- at no point did he ever admit to using any performance enhancing drugs ... or cheating in any way.

It's the first time the disgraced cyclist has acted remorseful since the cheating saga began several years ago.

After the apology, Armstrong met with advisers and his legal team before going face-to-face with Oprah at a nearby hotel.