Brian Rice lamented his side's luck this season after losing Aaron Martin just hours before Hamilton's 2-0 defeat to Kilmarnock.
The Accies manager had selected his team, including the experienced defender, only to be told at 11:30am that Martin would have to self-isolate after being contacted by track and trace.
Hamilton had kept consecutive clean sheets heading into the game at Rugby Park but the absence of Martin and captain Brian Easton through injury was a devastating blow.
Rice said: "Everything was done, we worked on the formation and set-plays. The physio rang me this morning and your heart sinks because you think something has happened.
"Brian Easton got injured last week and Aaron Martin got caught up in a track and trace situation. It wasn't until half past 11 this morning until I found out, so that changed things.
"Aaron is a big player for me, he's been fantastic since he came in and with Brian, he's held that back three together with either {Jamie} Hamilton or {Ben}Stirling.
"To lose the two of them coming here today was a big, big loss for us. I don't think Jamie would have done that with Aaron alongside him. You just have to take it on the chin and move on."
Hamilton have been decimated with injuries and covid-related issues and the absence of their key defensive duo showed.
Replacement George Stranger was unable to prevent Greg Kiltie from flicking home Youssouf Mulumbu's shot past Kyle Gourlay on 36 minutes.
Hakeem Odoffin headed Scott McMann's corner off the bar on 33 minutes but Hamilton failed to have a shot on target until the 90th minute. After Callum Smith's energetic run, Lee Hodson's tame effort was easily gathered by Danny Rodgers.
The visitors were well in the game without creating many clear cut chances until Kiltie capitalised on some poor defending from young Jamie Hamilton to curl home Kilmarnock's second on 63 minutes.
The 18 year-old defender, who attracted major interest from English Premier League clubs last season, has impressed in recent weeks alongside Martin and Easton but Rice believes he missed their presence.
He said: "We struck the bar at 0-0 but a bit of inexperience cost us at the second goal. Young Jamie Hamilton did something rash that he wouldn't normally do but we were missing our two main centre-halves from our last two clean sheets.
"We had a bit of inexperience in our central defence today and it cost us. I've said to the kid and he said he didn't see him. It's just inexperience and he needs to learn from that.
"There wasn't a great deal in it, Kilmarnock were the better team in the first half but we were still in it at 1-0."
After important victories this season, Hamilton have failed to build momentum as key players have missed subsequent fixtures.
Despite the transfer market opening and Rice being keen to add to his squad, the 57 year-old believes that the rise in coronavirus cases could scupper his plans to add new faces.
He said: "It's not just us who have problems but we have it severe and it'll happen to other clubs. We just can't seem to get that same team out and go on a run of having the same players available.
"Against Ross County, we had a great result then lost Ross Callachan and Scott Martin. We keep two consecutive clean sheets then I miss my two centre-halves today. We just can't get that break in terms of selection.
"It's going to get worse. It does effect the team selection and everything at the club. That's why we need numbers and we are actively trying to get players in.
"I thought I had two players last Friday then the covid situation changed and they've signed for an English club this week. It's very, very frustrating."
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