At 41, swimmer Dara Torres has faced enough challenges and fought enough battles to build a mental guard as tough has her rock-hard physique. But there is one subject that penetrates straight through her fierce competitor’s armor, and brought tears to her eyes as she spoke to TODAY’s Matt Lauer on Thursday. That is her coach, Michael Lohberg, who is conspicuously absent from these games.

“I feel like there’s a part of me missing, with him not being here,” Torres said.

Lohberg, 58, was diagnosed with aplastic anemia — a rare and serious form of cancer — shortly after the Olympic trials, where Torres twice broke the American record in the 50-meter freestyle to qualify for her fifth Olympic Games. This week, Lohberg should be on the deck of Water Cube, helping her make history once again by becoming the oldest swimmer to win gold. Instead, he is lying in a hospital bed in Maryland fighting for his life, leaving Torres to finish the journey for the both of them.

“It hasn’t been just about me ... because we’ve put such a team effort going into it,” Torres said.

Together, Torres and Lohberg conquered the physical obstacles that stood in the way of a 41-year-old mother making the Olympic team, but those are nothing compared to the mental challenge Lohberg’s absence poses to Torres now.

“I’ve never had this sort of hurdle to deal with emotionally when I’m in the biggest meet in my life,” she said. Talking to the team psychologist has helped her cope, Torres says, as has calling Lohberg two to three times a day.

“I need to hear his voice and know that he’s with me. Even though I kind of feel him with me, I still need that reassurance … I just tell him how well I’m doing and how much I feel him with me, and I that am doing this for us.”

Two years ago, when Torres decided to come out of retirement (for the second time) and attempt to add to her collection of nine Olympic medals, she turned to Lohberg. Together, they have built a meticulous and grueling training program that has allowed Torres to swim faster than athletes who weren’t even alive when she made her Olympic debut in 1984.

Their success has been so extraordinary, in fact, many skeptics say it is actually impossible without the use of illegal substances.

“It’s tough because there have been athletes who have looked the American media in the eye and said ‘I have not taken drugs and I never had’ and then a year later they’re in jail or they’re crying because they admit they have taken drugs,” Torres said, her emotional side quickly drying up as the fire in her personality took over. “It’s unfair that that has happened, and the minute that anyone does anything well or out of the ordinary, it’s assumed right away that they’ve taken drugs. Obviously, I’ve been accused of that.”

Torres has aggressively fought those accusations, submitting herself to the U.S. Anti-Doping Agency (USADA) for voluntary and rigorous drug testing of both blood and urine. The samples will remain on record so they can be tested again as drug screening advances.

“I would love in about five or seven years — when they retest the blood and urine that I’ve given — to sit down with those naysayers and say, ‘OK, I want an apology now,’ ” she said.

By that time Torres will be just another working mother. Torres insists this comeback is truly her last, this Olympics the final chapter of her illustrious competitive career. And it will be a chapter dedicated to Lohberg.

“It’s always been about Michael (Lohberg) and I, and us doing it together,” she said. “The one thing he said is, ‘Go finish what we started.’ ”

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