The Mooroopna product had the ball on a string as the last-placed Kangaroos fought back from 32 points down to defeat Hawthorn in the round nine classic.
Simpkin ended the game with a match-high 38 disposals, 13 clearances and nine tackles.
It was by far the best performance from the 23-year-old all season as he continues to become a household name in the AFL.
Simpkin was not alone in helping the Kangas to a 13.9 (87) to 12.8 (80) win.
Rochester's Shaun Atley collected 19 disposals.
For the Hawks, Shepparton export Jarman Impey recorded 20 disposals, Mansfield's James Cousins had 23 and kicked two goals, while Benalla's Harry Morrison notched 19 touches.
The dream run continues for Mooroopna's Clayton Oliver and his Melbourne teammates.
Oliver had a team-high 28 disposals to go along with his 10 tackles and seven clearances in the Dees’ 26-point triumph over Katandra export David Teague and his Carlton brigade.
The Demons remain in top spot on the ladder with nine wins to their name.
Another masterclass from David Mundy was not enough to help Fremantle get over the line against Essendon.
The Seymour product had 22 disposals, six clearances and one goal in the Dockers’ brutal seven-point loss.
After nine rounds this season, the 300-game-plus veteran would be close to leading Fremantle's best-and-fairest count.
Katamatite export Tom Clurey is set for an extended stint on the sidelines after breaking his jaw at the weekend.
The Port Adelaide talent clashed heads with an opponent during his side's round nine loss to the Western Bulldogs.
Clurey, 27, was subbed out of the game during the second quarter and watched on from the bench as the Power suffered a 15.6 (96) to 12.5 (77) defeat.
The key defender had surgery on Sunday to repair the damage to his jaw.
Port Adelaide said on Monday that Clurey would be sidelined for up to six weeks as he recovers.
Teammate and Echuca product Ollie Wines was best afield for the Power with 32 touches, while Kialla's Alex Keath stood up in defence for the Dogs.
Cobram export Esava Ratugolea helped Geelong to another strong win.
The former Yarroweyah and Cobram junior played in the ruck for the Cats on Friday night in the 21-point win against St Kilda.
Ratugolea ended the game with 13 disposals, five marks and four tackles.
Finley's Tom Hawkins booted two goals and registered seven marks in the win.
Lastly, Shepparton 2018 premiership teammates Lachie Ash and Jordy Butts battled strongly for GWS and Adelaide respectively in their round nine losses.
Tallygaroopna export Steele Sidebottom (25 disposals) was one of Collingwood's top performers in the five-goal loss to Sydney Swans.
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