Giants receiver Victor Cruz acknowledged Friday that he suffered a setback in his recovery from his strained left calf this week and added that he had a platelet-rich plasma therapy injection Thursday.

Though PRP therapy generally takes weeks to work, Giants coach Tom Coughlin said the team has no plans to put Cruz on injured reserve. Cruz said he fully expects to return to action eventually, even if he can't say when that might be.

"I haven't lost faith,'' said Cruz, who strained the calf in August after suffering a torn patellar tendon in his right knee last October that ended his 2014 season. "I know that my time is going to come. When that time is is still up in the air, but I know my time will come back here in a blue uniform with the New York Giants.''

Cruz had run some pass routes on a side field during Monday's practice and expressed optimism that he might be able to play in Sunday's road game against Rex Ryan's Bills.

He said Friday, however, that though he had been able to cut and do everything else without pain Monday, he ran at only three-quarters speed that day.

When he tried to run at top speed Wednesday, he felt pain in the calf, he said, and had to be shut down.

He admitted that this latest setback has been a huge blow for him. After undergoing season-ending surgery to repair his knee last year, he had been on track to return to the field in this year's preseason before straining his calf Aug. 17. Now he has to overcome the emotional letdown of having his return to action delayed again.

"You gear up for that moment when you want to be ready to play and ready to go out and perform and you have another setback,'' he said. "Hopefully it's the last setback.

"I'm going to continue to work hard, I'm going to continue to be the same person I am in regards to my work ethic, and the strength it takes to get back and to physically get back in that rehab room and to do the work you need to do in order to succeed and get back on the field.''

The PRP injection, he said, was something he did because doctors said that even if it doesn't help him recover faster, it won't set him back any further. He went for it, he said, because -- other than having a fear of needles -- he had nothing to lose by doing it.

Notes & quotes: Coughlin said rookie left tackle Ereck Flowers (ankle) is improving and might be able to play. "He was better [Thursday], seems to be a little better today," Coughlin said Friday, "so we'll put our heads together on that one for sure.''