Jack Sock's return from reported hip surgery has been delayed, meaning that he will not play next week's event in Memphis.
The 22-year-old, who withdrew from Hopman Cup and the Australian Open following surgery in the offseason, is still entered in Delray Beach in two weeks. He began training again three weeks ago.
He recently reached a career-high of No. 41, coming off a season in which he got to two ATP semifinals and won the Wimbledon doubles title with Vasek Pospisil.