Ben Watson’s first regular-season game back in a New England Patriots uniform won’t come until Week 5 at the earliest.

The veteran tight end announced Sunday in a lengthy Facebook post he is facing a four-game suspension after testing positive for a drug he was prescribed during his brief retirement earlier this spring.

“After my contract expired (in) March, I told my doctors I was finished playing, went through a series of medical tests and was prescribed Bio Identical Testosterone Cypionate to assist in healing my body and mind,” Watson wrote. “On March 29, nine days after I started therapy, I was randomly tested under our substance policies. I complied out of habit, never thinking in that moment I’d want to come back.”

Watson, who spent last season with the New Orleans Saints, ultimately did decide to continue his career and began negotiating with teams in late April. He said he received word of his failed test and impending suspension May 3 and “immediately” informed the Patriots, who, despite the month-long ban, signed him to a one-year, $3 million contract May 9.

The 38-year-old said he will not appeal his punishment.

“I am excited and thankful to return to New England but very disappointed that I will not be able to play and contribute immediately,” wrote Watson, who played for New England from 2004 through 2009. “This is not how I would want to enter a new locker room and attempt to earn my role on a new team. However, I respect the regulations that have been collectively bargained to promote fairness on the field of play and accept the discipline associated with my infraction.”

As the days and weeks of the 2018 football season passed, I was certain that it would be my last. Injuries and health…

Posted by Benjamin Watson on Sunday, May 26, 2019

Watson had been projected as New England’s No. 1 tight end following the offseason departures of Rob Gronkowski (retirement), Dwayne Allen (cut) and Jacob Hollister (trade). Austin Seferian-Jenkins, Matt LaCosse, Ryan Izzo, Stephen Anderson and Andrew Beck now will vie for that spot to start the season, with a trade for a veteran like Kyle Rudolph still in play.

LaCosse, who signed with New England early in free agency after 17 games with the Denver Broncos, impressed Thursday in the Patriots’ first open practice of organized team activities. Seferian-Jenkins was excused from the first week of OTAs for personal reasons.

Under NFL rules, Watson will be allowed to participate in spring practice, training camp and preseason games. He will not count toward the Patriots’ 53-man roster until he is reinstated ahead of New England’s Week 5 matchup with the Washington Redskins.

Thumbnail photo via Zack Cox/NESN