The dust had barely settled on University's win in the Lovelock Relay two weeks ago when Roy (19) led her team to the club's first win in the Leith relay for 12 years.
The relays were first contested in 1981 and this is only the third time University has won the women's event.
It also won in 1997 and 1998.
It was the same University team that won the Lovelock Relay, with Roy joined by Andrea Peat, Grace Fursdon and junior international Hannah Newbould.
They were up against a proven Hill City club that had won the title 14 times and was the defending champion.
Newbould got her team off to a flying start with a 16sec lead over cross-country international Rachel Kingsford, who was the Hill City runner on the first of the four 2km legs.
Peat ran solidly on the second leg and extended the lead over international triathlete Taryn McLeod to 27sec.
But junior international Rebekah Greene brought Hill City back into contention when she overtook Fursdon to give Hill City a 1sec lead before the final change.
Roy quickly caught international marathon runner Shireen Crumpton and gave University a win by 28sec.
University was first in 31min 23sec, Hill City next in 23min 51sec and Leith third in 32min 57sec.
"I felt good and fresh so I went for it," Roy said at the finish.
"I was frightened to look back so I used the downhill and crowd support to speed up."
Caversham retained the senior men's title after a race of changing fortunes.
Daniel Balchin ran the fastest time on the last of the four 3km legs with 8min 56sec to win the race for Caversham in a team time of 37min 11sec.
Ariki was 11sec back in second place and Hill City third in 39min 5sec.
Steve O'Callaghan (Leith No 2) led after the first leg when he beat international mountain runner Dougal Thorburn (Ariki) and Lyndon Brown (Caversham).
Caversham was 32sec behind the leaders at that stage.
It became a two-team race between Ariki and Caversham from the second leg.
Ariki overcame the 4sec deficit on the first leg to take the lead with strong runs by Tim Dobier and Callan Moody on the second and third legs.
Tony Payne brought Caversham back into contention on the second leg and Peter Meffan kept Caversham in contention on the penultimate leg.
Balchin had 10sec to make up on the final leg and he quickly hauled in Otago cross-country champion Nathan Baxter (Ariki) to win the title for Caversham by 11sec.
