The tennis ace stopped traffic as he saw the labradoodle running towards oncoming cars at the weekend then returned it to its startled owner.
Speaking at Wimbledon this morning as her son prepared for his next match, Judy Murray said her reaction was: "What you doing? You're on the way to Wimbledon and you're going to get run over."
She said the dog's owner was shocked to see who had saved her pet.
"Andy was sitting in the car and she just went, 'Oh my God'."
Ms Murray was remaining coy about rumours she is to star in Strictly Come Dancing, but made it clear who she would like as a partner.
She said: "Don't believe everything you read in the papers."
But when asked who she would like to have as a professional partner on the show, if she were to take part, she immediately said: "Artem."
Artem Chigvintsev is one of the programme's professional dancers.
Asked if she thought she would progress towards the final in the BBC show, she said: "I'm only going to be watching it on television."
The 54-year-old tennis coach is a big fan of Strictly and has posted comments about the dancers on her Twitter account.
She is believed to be in the advanced stage of talks to join the next series.
Surrounded by a press pack, Ms Murray, who was serving up coffee to fans in the queue, was asked why she would choose Chigvintsev.
"Because I think he is a phenomenal dancer and I love watching him dance," she said.
Echoing Sir Bruce Forsyth's catchphrase, she added: "He's my favourite."
Asked if Chigvintsev's toned chest had anything to do with her preference, she joked: "That's not bad either. That helps!"
Ms Murray was also coy about bookmakers closing betting on her son getting engaged to girlfriend Kim Sears during the tournament - and her views on the Scottish independence vote.
She volleyed back questions on both with "no comment" replies.
Shortly after Murray's match against Rola got under way, the glamour of Wimbledon sounded with the pop of a champagne cork, amusing the spectators.
Meanwhile, William Hill has shortened the odds on Maria Sharapova and Grigor Dimitrov getting engaged before the end of the men's final from 25/1 to 10/1.
The bookmaker is offering odds of 10/1 that Ms Murray hits the Strictly dancefloor.
Murray powered to victory, needing just an hour and 24 minutes to see off Rola 6-1 6-1 6-0.
He was congratulated on his win by the Duchess of Cornwall as he bumped into her on his way back to the locker room, a royal spokeswoman said.
Elsewhere, British hopeful Tara Moore lost her match against former world number one Vera Zvonareva.
Moore was being sponsored for fist-pumping during her match, with funds going to the charity Rally for Bally which was set up in memory of the late tennis player Elena Baltacha.
The sponsor, mobile network Three, estimated that there were 171 fist-pumps during the match and, with £3 donated each time, £513 was raised.