GEELONG has held off an undermanned Port Adelaide for a thrilling 12-point win to breathe life back into its AFL premiership defence.

Ollie Henry kicked a career-high four goals and Gryan Miers was creative forward of centre in the 14.13 (97) to 12.13 (85) victory at GMHBA Stadium on Saturday night.

It put the Cats back into the top eight on percentage ahead of Carlton, which has a game in hand.

Off-season recruit Henry starred early, with four goals to his name by the opening minutes of the second quarter, while Miers (24 disposals) kicked two goals and had a direct hand in five others.

Experienced guns Isaac Smith (22 disposals, one goal) and Patrick Dangerfield (20, one) were also influential and key pair Tom Stewart and Esava Ratugolea stood up in defence.

Port Adelaide's fourth straight defeat left its top-two spot in jeopardy and came amid a raft of injuries and illnesses.

The Power made six forced changes, with Jeremy Finlayson and Miles Bergman (both illness) late withdrawals before losing Trent McKenzie to a knee injury in the opening 10 minutes.

It got worse when Todd Marshall, crucial in the absence of fellow tall forwards Charlie Dixon (foot) and Finlayson, jogged off before quarter-time after hitting his head on the ground in a diving attempt to mark.

Power officials had come under intense scrutiny over their botched management of Aliir Aliir's concussion protocols and took no risks with Marshall, sending him downstairs for further assessment.

Marshall was cleared to return and kicked a pair of important goals from strong marks either side of three-quarter time.

The second put Port in front early in the final term but Geelong finished stronger, kicking four of the last five goals.

Midfield stars Zak Butters (30 disposals, one goal) and Connor Rozee (27 touches) were brilliant for Port and Willie Rioli finished with four goals, while Sam Powell-Pepper kicked three.

Both sides took advantage of perfect conditions in a free-scoring first quarter as Rioli and Henry booted three goals apiece.

Henry's third sailed through after the quarter-time siren to give the Cats a 44-31 lead at the first break.

Henry's purple patch continued with the first goal of the second term and Geelong extended their advantage to 17 points by half-time.

A brilliant Powell-Pepper snap sparked the Power early in the third quarter and they gained confidence, piling on four goals to one for the term.

Marshall put them in front again in a game where the lead changed six times, before the Cats won the arm wrestle between two desperate sides in a tough final quarter.

Jeremy Cameron kicked two goals for Geelong and Mitch Duncan (one) was important in attack.

Port needs to break its losing habit
Saturday's loss was Port Adelaide's fourth in a row, coming off the back of 13 straight wins and, depending on other results, could see the Power out of the top two by the end of the round. None of the defeats were a massive surprise as they faced quality opposition, but losing form is never good form and can start getting into players' heads. With just three rounds to go before finals Ken Hinkley will be desperate for his side to get back on the other side of the ledger, starting with next week back at Adelaide Oval against GWS.

Big Cat's big influence
Esava Ratugolea started the season well in his new role as a key defender but was dropped to the VFL ahead of round 18 after his influence waned. Injuries to Tom Hawkins and Mark Blicavs saw the big man recalled and he immediately went back to work as a spring-heeled intercepter. Learning a whole new game takes time and it was reasonable for Ratugolea to have trouble keeping up his early high standards, but if Geelong is to be any chance of a premiership defence it's going to need him patrolling the back half with his strong hands and easy leap.

Kids at the wheel but they're no P-platers
The Power were in the contest till the end due to the trio of Zak Butters, Connor Rozee and Jason Horne-Francis, who were in everything from the outset. While the threesome have had their praises sung loud and often this season, it's easy to forget just how young they are. Rozee is the elder statesman at 23, Butters is 22 and Horne-Francis a mere 20, meaning they're likely to be driving this side for the next decade. To have an engine room of that quality locked and loaded for such a long period is a luxury every other club can only dream of.

GEELONG              7.2    9.5    10.9    14.13 (97)
PORT ADELAIDE    5.1    6.6    10.8    12.13 (85)

GOALS
Geelong: O.Henry 4, Miers 2, Cameron 2, Stengle, Smith, Duncan, Dangerfield, Bowes, Close
Port Adelaide: Rioli 4, Powell-Pepper 3, Marshall 2, Horne-Francis, Butters, Boak

BEST
Geelong: Miers, Dangerfield, Stewart, Smith, O.Henry, Stanley
Port Adelaide: Rozee, Butters, Horne-Francis, Burton, Boak, Rioli

INJURIES
Geelong: TBC
Port Adelaide: Trent McKenzie (knee)

LATE CHANGES
Geelong: None
Port Adelaide: Jeremy Finlayson and Miles Bergman, replaced in the selected side by Jase Burgoyne and Riley Bonner 

SUBSTITUTES
Geelong: Brandan Parfitt (replaced Jack Henry in the third quarter)
Port Adelaide: Jackson Mead (replaced Trent McKenzie at quarter-time)

Crowd: TBC at GMHBA Stadium