McIntyre, competing in her first ever Olympics, is joining reigning champion from Rio 2016 Mills in her bid to defend her crown.
The Great Britain pair were placed fourth overall after getting their quest for glory under way on the Enoshima waters earlier today.
McIntyre, aiming to follow in father Michael's footsteps and claim Olympic gold on the water, and Mills then moved up a place to third in the standings after the second and final race of their first day of action.
Polish pair Agnieska Skrzypulec and Jolanta Olga currently top the leaderboard while France's Camille Lecointre and Aloise Retornaz sit above the GB duo in second position.
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While McIntyre's Olympic quest is getting up and running, former Crofton School pupil Beccy Muzerie's Games are now over.
She was part of the women's eight rowing team who finished in the fifth and final spot in the repechage in the early hours.
The Team GB eight were handed a second chance to qualify for the semi-finals after finishing fourth in their heat of Sunday.
However, they could only finish last in the repechage which saw them eliminated from the Games.
Meanwhile, goalkeeper Maddie Hinch was part of the Team GB women's hockey side who secured a second successive pool A victory.
Hinch, originally from Hill Head, saw her team-mates claim a 4-1 triumph over India.
The reigning Olympic champions from Rio lost their opener to Germany but they have now clinched successive 4-1 wins over South Africa and India.
Next up for Team GB is a meeting with the Netherlands tomorrow.