Law described it as a "huge relief", having been one of many tennis pundits, players and officials to be worried about Sears' health scare.
Murray, whose wife Kim Sears remains at home and is due to give birth in February, was initially oblivious to the situation on Saturday night.
The second seed only learned of Sears' setback after beating Portugal's Joao Sousa in four sets on Margaret Court Arena.
Murray rushed to hospital, understandably cancelling his on-court interview and post-match press duties.
Thoughts of a fourth-round match against Bernard Tomic would have been the last thing on Murray's mind overnight.
"I'm very sorry. I heard briefly what happened quickly," Tomic said, the same week his first-round match was delayed for more than 20 minutes while a spectator received medical treatment.
"It's a bit personal to get into that. I don't know as much as you do.
"For his sake, it's bad luck.
"I wish him the best. I'm sure it will have no effect for him when he plays on Monday."
Sears underwent tests on Saturday night but was in good enough shape to ask for a TV so he could watch Ivanovic's three-set loss to Keys.
Murray has previously said he plans to put family first and leave Melbourne mid-tournament should Kim Sears go into premature labour.
Ivanovic was visibly concerned after the incident and showed immense mental strength to return to court in a 4-6 6-4 6-4 loss to Keys.
Play had been suspended for almost an hour.
- AAP