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The 32-year-old royal left her baby daughter Mia at home in Gloucestershire as she attended Aintree racecourse to see Mike's horse, Monbeg Dude, who came in at seventh place.
Zara sported a chic cornflower blue coat for her sporty outing, topping her blonde locks with an elegant navy blue hat, complete with a monochrome patterned feather.
Joined by her mother Princess Anne, mum-of-one Zara accessorised her look with towering black heels and a black envelope-style clutch bag.
Earlier on Saturday, Mike tweeted his excitement about his racehorse's upcoming appearance at the famous race.
"Thanks for all the good luck messages for #thedude," said Mike. "Hope he has a good spin and most importantly comes home safe! #comeontheDude."
Zara's cousin Princess Beatrice was among those cheering on Monbeg Dude.
"Good luck to #MonbegDude and #LongRun for this afternoon's grand national," tweeted the Princess. "I will be watching at 4 15 I'm so excited."
Mike, 35, also tweeted his thanks to Britain's Got Talent judge Amanda Holden who drew Mike's horse in a sweepstake on comedian Alan Carr's Channel 4 show Chattyman.
Zara Phillips and Mike Tindall introduce their beautiful daughter Mia
"Congrats to @Amanda_Holden on getting #thedude in @chattyman #crabbiesgrandnational2014 sweepstakes @Channel4Racing," he wrote.
In an interview with the Daily Mail rugby star Mike revealed that his wife Zara called him an "idiot" after he told her he had bought Monbeg Dude for £12,000 last year.
Zara Phillips take Mia to her first rugby game
The Queen's granddaughter was not only bemused because Yorkshire-born Mike had not planned on the extravagant buy, but also because he knew nothing about the horse in question.
Luckily for Mike, however, his spur-of-the-moment purchase has worked out rather well and Monbeg Dude came out on top at the Welsh Grand National in Chepstow in 2013 and has gone from strength to strength since.
"I like to bid in auctions without meaning to actually win things" Mike explained. "I only went for a bite to eat and a night out.
"No horse had gone for less than £28,000 so I thought my first bid of £10,000 was pretty safe, likewise when I upped it to £12,000," he added. "I knew nothing about the horse, hadn't checked the brochure and couldn't see the Dude as I was sitting with my back to the sale ring."