The pair yesterday dead-heated for third place in the National Championships in Eugene, Oregon – which double as the Olympic trials – with an initial announcement to the crowd suggesting Tarmoh had been given the verdict by 0.0001 seconds before the results were then reviewed.
With no tiebreak procedure included in USA Track and Field's regulations, the governing body considered their options before announcing that both athletes will be given the choice of a run-off or a coin toss. If Felix and Tarmoh disagree on their preferred method then a run-off will be used, but if neither declares a preference then a coin-toss will be used.
Justin Gatlin ran 9.80 seconds to win the men's 100m and qualify for his second Olympics along with Tyson Gay (9.86) and Ryan Bailey (9.93).
A confident Gatlin said: "I knew I had to get out of the blocks, keep the middle flawless, bring it home precisely and have the technique coming through the line.
"I have a lot left in the tank. This season so far has been undefeated and I'm just trying to ride that wave."
Gay added: "I feel pretty good, just excited to make the team.
"I feel like I'm on my way up. This is only my second race of the year and I only started training in March."
Bailey's better-known team-mate Walter Dix was beaten into eighth place in the final and said: "Things like this happen. I really can't say much about it. I'm just glad my team-mate Ryan Bailey made it through."
LaShawn Merritt – who like Gatlin has returned from a drug ban to earn selection – ran a world-leading 44.12sec to win the men's 400m. Tony McQuay and Bryshon Nellum ran personal bests to join Merritt on the Olympic team.
"This won't be my first rodeo," said Merritt. "I will go in confidently, and I am definitely confident in Tony and Nellum that they can handle this.
"They came out of college and now they're with the big dogs – it's a different mentality to run with someone who can run 44.8 in the first round."
Sanya Richards-Ross secured her place in the women's event in even more emphatic fashion. Her time of 49.28sec was also the best in the world this year and gave her a winning margin of 0.74sec ahead of fellow qualifiers DeeDee Trotter and Francena McCorory.
"Today was phenomenal," said Richards-Ross. "It's a dream come true. I'm excited to (represent) Team USA."
Marquise Goodwin produced a PB of 8.33m to defend his national championship in the men's long jump and qualify first ahead of Will Claye. George Kitchens Jr was third, helping to lay the ghost of 2009 when he was third with a wind-assisted jump but was not selected for the World Championships as he had not achieved the A standard with a legal jump.
A similar fate befell Suzy Powell-Roos in the women's discus, as she finished third but without having made the A standard. The third ticket to London instead went to sixth-placed Gia Lewis-Smallwood, the highest-placed athlete with the A standard after leading pair Stephanie Brown-Trafton and Aretha Thurmond.
Lewis-Smallwood said: "It's my first Olympic Team. I'm happy about that. I wish I could have placed higher, but I made it."
Reese Hoffa, who set a world-leading mark, Ryan Whiting and Christian Cantwell took the three places in the men's shot put while 2008 silver medallist Jenn Suhr was joined in the women's pole vault squad by Becky Holliday and Lacy Janson.