"Every time I play on it, it's making it worse. You never know how much damage you can do to yourself, you just hope it doesn't get so bad you can't play.
"Four or five days [rest] isn't enough."
Murray, who was out for three months when he injured his right wrist in 2007, admitted he is unsure how long it will take to heal but will see a specialist before deciding whether to play on or not.
"If it takes four months to get better, it takes four months. If it takes a week, then it'll take a week," he added.
"I'll go back up to London, I'll go see the specialist I saw when I hurt my right wrist and make a decision on what I'm going to do next."
And Murray hinted that criticism he received for missing previous Davis Cup matches was one of the reasons he decided to risk the injury against Poland.
Asked whether he came close to missing the tie, he said: "I thought about it but last time something like that happened I spent the next three months answering questions like, 'Are you dedicated enough to play for your country? Does Davis Cup mean anything to you? Is it important enough? Do you feel like you let your country down?'
"It's pathetic. I play hard and I've always enjoyed playing for my country. I came up here on Sunday with the rest of guys, I practised hard.
"I love being around a team atmosphere and every time I feel fit enough to play Davis Cup, I'll play. If I'm not feeling well or I'm hurt, then I can't."
Murray playing through pain barrier
GB captain John Lloyd revealed Colin Fleming will partner Ross Hutchins in Saturday's doubles if Murray is unable to play.
"I would love Murray to play but he's a professional athlete and he knows his body a lot better than I do," said Lloyd.
"He'll go as far as he can but if he can't play three matches, he can't play three matches. I don't know what he's going to say.
"You would think the logic would be to give him another 24 hours rest, give it more chance so that he'd be OK for the singles.
"But then obviously in doubles it does lessen our chance if he is not in and we are taking the risk on it going into the fifth match.
"That could have happened anyway even with Andy playing with Ross, you would still, on paper, make the Poles favourites in the doubles."
The crowd at Liverpool's Echo Arena gave Murray an enthusiastic welcome as he made his first appearance since losing to Marin Cilic in the last 16 at Flushing Meadows.
The 22-year-old capitalised on a couple of sloppy errors from Przysiezny to break in the third game, but was matched the rest of the way in opener.
After Przysiezny clung grimly to his serve in a protracted opening game of the second, Murray accelerated away with breaks in the third and fifth to move into a 2-0 lead.
The third game again proved crucial in the third set as Murray edged ahead and, after a brief wobble as he was taken to break point in the eighth, it proved enough for victory.
Evans, 19, endured a difficult Davis Cup debut as he was comfortably beaten 6-3 6-3 7-6 (7-5) by fellow teenager Janowicz in the day's second match.
Illnesses to both James Ward and Josh Goodhall, who could have been expected to play the second singles match, handed the Birmingham-born player a starring role.
Highlights - Evans beaten by Janowicz
Evans recovered from a break in the opening game of the match, but the world number 302 promptly slipped behind again in the seventh.
A double fault at 5-3 down offered Evans' big-serving opponent three set points, the Pole taking the last courtesy of a double fault.
A mishit shot just clipped the tramline to give Janowicz a crucial break in the sixth game of the second set.
The 18-year-old then clambered back from 0-40 down in the ninth to seal the set with five consecutive points.
Although Evans battled on stubbornly the third set was eventually wrenched from the UK number five as Janowicz powered through to level the tie.
Depending on whether he opts to rest his wrist, Murray may return to action alongside Ross Hutchins in Saturday's doubles match against Mariusz Fyrstenberg and Marcin Matkowski.
And Lloyd declared himself satisfied with how the first day had panned out.
"On paper it's turned out the way it was supposed to," he said.
"Obviously I didn't think there was any way Andy was going to lose.
"(The second singles) would have been a nice one to win but Janowicz showed the sort of ability he has and I thought Dan overall played pretty well but just couldn't quite hold him close enough."
On Sunday, the reverse singles match-ups bring the contest to a close.
The winner of the Europe/Africa Zone play-off will hold on to their Group I status while the losers will be relegated to Group II.
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