HARRISON Petty and Jacob van Rooyen have had career-best days in attack with a combined 10 goals to propel Melbourne to a runaway 32-point win over Richmond at the MCG on Sunday afternoon.

The Demons, who twice fell 20 points behind after half-time, edged closer to a top-two spot with their 20.10 (130) to 15.8 (98) victory in a classic contest.

Former defender Petty (six goals), young gun van Rooyen (four), and veteran Jake Melksham (four) fired as the key targets in an attacking mix that gave Simon Goodwin food for thought as he ponders axed recruit Brodie Grundy's future role in the side.

One of Melksham's majors included the goal that marked the sixth lead change in a see-sawing contest to put the Demons in front for the final time midway through the last quarter.

They finished far stronger than Richmond, kicking the last six goals of the game to post their highest score since round seven and settle a gripping battle in front of 52,294 fans.

Melbourne's Jack Viney (32 disposals, seven clearances), Christian Petracca (29, eight) and Max Gawn (28, 11) were outstanding.

Captain Gawn, who also had 40 hit-outs and 22 contested possessions, was particularly influential when the game was on the line in the last quarter.

The Demons remain in fourth spot on the ladder but moved closer to the top three after Collingwood, Port Adelaide and Brisbane all lost in round 20.

Richmond would have climbed into the top eight if it had won but was left kicking itself after letting its lead slip.

Tim Taranto (24 disposals), Jacob Hopper (23) and Shai Bolton (25) all fought hard in a losing battle, while Tigers superstar Dustin Martin kicked 3.2 from 21 disposals and had 11 score involvements.

Martin booted two majors in the third quarter, including one from the centre square, as Richmond surged ahead in slippery conditions.

They looked likely winners when Martin's long-range shot sailed through at the six-minute mark of the third term, but the lead had evaporated by three-quarter time.

The Demons kicked five of the next six goals and added another 6.4 to 2.0 in the final term.

Noah Balta's goal 10 minutes into the last quarter had put Richmond in front but they were no match for Melbourne when it mattered most.

02:17

RD 20 | Petty party as six-goal show uncovers new weapon

Melbourne's decision to start Harrison Petty as a forward pays off beyond belief with a stunning return of six majors.

Petty finds the ball - and the big sticks - at will
Have the Demons finally found what they've been looking for in attack? Judging by Harrison Petty's output up forward, the answer could be a 'yes'. The swingman, who played much of his career as a backman, showed his versatility as he booted a career-best six goals. But it wasn't only the goals that put Petty in the spotlight, with the 23-year-old also taking a game-high 10 marks (including four contested) and had nine score involvements in a dominant showing that is sure to please coach Simon Goodwin on the eve of finals.

RICHMOND      5.4    9.7    13.8   15.8 (98)
MELBOURNE    3.5    8.5    14.6   20.10 (130) 

GOALS
Richmond: Martin 3, Baker 2, McIntosh 2, Balta, Bolton, Coulthard, Prestia, Riewoldt, Rioli, Soldo, Taranto
Melbourne: Petty 6, Melksham 4, van Rooyen 4, Pickett 2, Chandler, Hunter, Neal-Bullen, Petracca

BEST
Richmond: Martin, Bolton, Taranto, Prestia, Baker
Melbourne: Petty, Gawn, Viney, Melksham, van Rooyen, Rivers

INJURIES
Richmond: None
Melbourne: None

SUBSTITUTES
Richmond: Matthew Coulthard (replaced Ben Miller in the third quarter)
Melbourne: Joel Smith (replaced Adam Tomlinson in the third quarter)

Crowd: 52,294 at the MCG