Althiqa led the first two home for Godolphin trainer Charlie Appleby in the Grade 1 Diana Stakes at Saratoga on Saturday.
The Dark Angel filly collared stable companion Summer Romance close to home over the nine-furlong trip to win by three quarters of a length.
The Godolphin pair had previously battled over a mile in the Grade 1 Just A Game Stakes at Belmont Park in June, when Summer Romance made the running before being headed by Althiqa.
Summer Romance, under Luis Saez, once again adopted her front-running tactics, with Manny Franco on Althiqa settling in sixth on the outside of the field.
Althiqa took closer order leaving the back straight and accelerated strongly down the centre of the track entering the final furlong, heading her stable-companion with just over half a furlong to race.
Summer Romance rallied but could not go on with Althiqa, who saw out the trip cosily to take her head-to-head record to 3-1.
“We had two big Grade 1 targets with these fillies and we couldn’t have done better,” Sophie Chretien of Godolphin told their website.
“Summer Romance didn’t win the rematch with Althiqa, but what I realised with Althiqa with all the time she’s been with us, she is becoming stronger physically and mentally. Summer Romance is a lot more of a nervous filly.
“It’s a great feeling. It’s my first time coming to America and you don’t know the tracks, but these horses are smart. You just have to listen to them.”
Althiqa’s second Grade 1 success took Godolphin’s tally for the year to 10 Group 1s and Appleby’s fifth.
“I just wanted to wait as long as I could with Althiqa because I knew the distance was further than her last race,” Franco said.
“The trip was the question, but she did it. She was so relaxed behind horses and then she gave me a nice move and a nice kick.”