Thomas' recovery will take at least six months, and he could, depending on the severity of the injury, miss all of next season.
"Heading to surgery this morning.. everyone keep me in prAyers that it goes well," Thomas tweeted Monday morning.
Earlier, he tweeted about his mother and grandmother, who have been incarcerated on drug charges since he was 12: "Only if i had my mother and granny here with me, stuff would be so different.. Miss y'all and love y'all"
Thomas had a tough year after leaving Georgia Tech following his junior season. He fractured his left foot during pre-draft workouts, but he still was the first receiver selected in the draft when the Broncos chose him at No. 22, three spots ahead of their other first-round pick, quarterback Tim Tebow.
Thomas was just starting to flash his athleticism and mobility, using his 6-foot-3, 230-pound frame to outjump defenders, when he re-injured his surgically repaired foot early in training camp and didn't return until after the opener.
Thomas had a spectacular debut in Week 2, catching eight passes for 97 yards and one touchdown against the Seattle Seahawks, but he never tallied more than three catches in any game the rest of the season. He was knocked out of one game with a concussion while returning a kickoff and was sidelined for the final five weeks of the season with a sprained ankle.
Thomas played in 10 games, starting twice and finishing with 22 receptions for 283 yards and two scores. He also returned 16 kicks for a 24.9-yard average.
Thomas showed enough promise, as did fellow rookie Eric Decker, for new coach John Fox to proclaim upon his hiring that the receiving corps led by Pro Bowler Brandon Lloyd and Jabar Gaffney was the area that needed the least attention during the team's massive makeover.
That has changed.
Royal's surgery briefly opened a window for Thomas to see more playing time, but he was hurt Wednesday while working out in Atlanta, where he lives during the offseason.
The Broncos might now have to consider drafting a wide receiver in April.
Copyright 2011 by The Associated Press