Supercars great Jamie Whincup has apologised to his team manager after ignoring instructions to let teammate Shane Van Gisbergen pass amid a drama-charged duel which may have cost them a race victory.

Tensions were running high after the championship-leading teammates fought a fierce wheel-to-wheel battle which helped youngster Will Brown to claim his maiden Supercars win at Sydney Motorsport Park on Sunday.

With eight laps remaining Van Gisbergen was on Whincup's bumper as they closed on leader Brown, their cars touching several times as the Kiwi fought to pass.

"Why am I being run off the road?" Van Gisbergen asked on his team via radio after Whincup held a firm line outside turn three, forcing series leader Van Gisbergen off the asphalt.

Whincup was told by Red Bull Ampol team manager Mark Dutton to let Van Gisbergen through as his fresher tyres posed a greater threat to Brown.

But the seven-time Supercars champion wouldn't have a bar of it, continuing to block and suggesting his teammate should work with him to catch the front runner.

While they finally closed, they were unable to get past Brown as Whincup held on for second with Van Gisbergen third.

"I felt like I had the faster car," said Whincup.

It felt like SVG (Shane van Gisbergen) was racing us rather than the field which was disappointing, and I had to race both him and try to get the lead from Will.

"I was keen to keep him behind me, he was keen to pass me, and unfortunately that meant that none of our cars won.

"I understand there were team orders from Dutto that I didn't adhere to, and I apologised to him for that."

Van Gisbergen saw his championship lead reduced but he still has a commanding margin with 2678 points ahead of Whincup on 2341, with one more Sydney round then the season-ending Bathurst 1000 to come.

I felt like Jamie and I battled too hard and threw away a one-two for the team by choosing to battle," said Van Gisbergen.

"I thought I was quicker, and Jamie thought he was quick enough to catch the lead."

Dutton was diplomatic about the incident which threatened team harmony in the season's closing stages before Whincup retires to take a senior team management role next year.

"It's just one of those things that we saw one way and from the cockpit it was seeing other ways so we'll debrief that and we'll have a chat about which was the right way and which was the wrong way," Dutton said.

"We'll discuss it professionally and we'll move on."

It was a memorable day for young gun Brown who - after two podium finishes and a maiden pole in recent weeks - became the 82nd driver in the history of Australian Touring cars and Supercars to win a race.

Starting in fourth, a decision to pit on lap 14 with a blistering 3.7 second stop poised the 23-year-old for a barnstorming finish, one that he admitted had him sweating.

"I was sort of shi**ing myself when they were catching me, I thought 'oh it's on here'," Brown told Fox Sports.

"I thought if I could bank them up into each other they'd dog fight against themselves which is what ended up happening.

"That was nerve-racking at the end but just bloody awesome."

The winner of Sunday's earlier race, Anton De Pasquale, could only finish 11th in the closing race, but the Shell V-Power driver was still the man in form following five wins from the last nine races, all at the Sydney venue.

De Pasquale has mounted a sustained attack on the championship standings, inching closer to the top five with his red-hot form.

RACE 28 RESULTS:

1. Will Brown (Erebus Motorsport)

2. Jamie Whincup (Red Bull Ampol Racing) +0.280

3. Shane Van Gisbergen (Red Bull Ampol Racing) +0.522

4. Nick Percat (Brad Jones Racing) +6.568

5. Todd Hazelwood (Brad Jones Racing) +7.413

RACE 27 RESULTS:

1. Anton De Pasquale (Shell V-Power Racing)

2. Jamie Whincup (Red Bull Ampol Racing) +6.087

3. Shane Van Gisbergen (Red Bull Ampol Racing) +9.952

4. Chaz Mostert (Mobil 1 Appliances Online Racing) +9.960

5. Will Davison (Shell V-Power Racing) + 12.117

CHAMPIONSHIP STANDINGS:

1. Shane Van Gisbergen (Red Bull Ampol Racing) 2678 pts

2. Jamie Whincup (Red Bull Ampol Racing) 2341 pts

3. Will Davison (Shell V-Power Racing) 2149 pts

4. Chaz Mostert (Mobil 1 Appliances Online Racing) 2083

5. Cameron Waters (Monster Energy Racing) 1964 pts