The former Leeds, Wigan, Warrington and Castleford player came off during the Wildcats' 44-24 Super League defeat at Wigan on Sunday with a foot injury but revealed he sustained the rupture from his first carry of the match and played on with it.
He was admitted to St James' Hospital in Leeds 24 hours later after discovering the extent of the damage to his right testicle and had surgery to remove a blood clot.
Speaking from his Leeds home, Mathers, 29, said: "Darrell Goulding's knee caught my right testicle by accident and I felt it all the first half, although it wasn't excruciating. I then went over on my foot and came off with that. I literally stayed up all night icing my foot and I was like a zombie when I went to training yesterday.
"It was only when I went for a shower that I noticed the testicle had swollen a fair bit and I showed it to the doctor, who sent me straight for scans."
The incident is the second of its kind in Super League in the last six months. Warrington prop forward Paul Wood revealed in the aftermath of his side's Grand-Final defeat by Leeds last October that he suffered a ruptured testicle and had to have it removed in hospital.
"It's been a 24-hour emotional roller-coaster," added Mathers, who captained Wakefield at Wigan in the absence of injured skipper Danny Kirmond. "The crazy thing is I was more concerned about my foot.
"The testicle had swollen to the size of a tennis ball and gone black and they spoke about counselling because it looked like I would lose it. But, when I woke up this morning, they said they had managed to save it so I was pretty relieved. I was luckier than Paul.
"I must thank first and foremost the club doctor John Lynagh and I can't praise the staff of St James' enough for how quickly and sympathetically they dealt with me."
Mathers has been ordered to have complete rest for a fortnight, during which time he will also check out the extent of his foot injury. He also intends to wear protection around his groin in future as a precaution in case of further injury.