In front of a loud and passionate Happy Valley crowd of around 11,000, each of the four legs went to a different jockey, with none among De Sousa, Marquand, Vincent Ho and Derek Leung able to add a scoring place that would have separated them from the pack.
The joint-champions were named on countback, with De Sousa and Marquand sharing HK$700,000 on account of both riders notching a fourth placing earlier in the evening, though at the half way stage neither had scored any points.
“To finish joint-top with Silvestre is pretty epic,” said Marquand, who finished tied for second behind Zac Purton here 12 months ago. “He's been champion jockey back home, he works so hard and is someone you look up to in the weighing room.
“It's a huge honour and sometimes you have to pinch yourself that these things are happening.”
Winner of the IJC in 2018, De Sousa secured his half of the title when clinging on aboard Adios for Frankie Lor in the final leg.
De Sousa said: “I never say die and I was just thrilled to win for Frankie because he has supported me here since day one. I thought Adios in the final leg was my best chance and he has come out and proved that.”
De Sousa added: “I'm just delighted. It's my second time winning and I finished placed another time. In the last leg I just felt the crowd and although it was a long last half furlong, thank God he got his head down and we gave it everything.”
Marquand got on the board in Leg 3 when hugging the rail aboard Winning Dragon before driving the Chilean import past Red Majesty, leaving him in pole position courtesy of his effort in Leg 1.
Speaking after Winning Dragon's success, Marquand said: “For the last couple of years we couldn't help but walk away feeling we probably got half the experience without crowds. But it's an unbelievable achievement from the Hong Kong Jockey Club to have kept it going and it's wonderful to have the crowds back and get the full IJC experience.”
De Sousa had the weight of favouritism to contend with when getting the leg up from Lor on Adios in the concluding heat but showed typical steel to guide the 2/1 market leader home, holding off the late charge of Red Lion to score by a short head.
Such was the finely-balanced nature of this IJC that Jamie Kah would have swept past both her rivals had Red Lion got there in the dying strides.
In the end that razor-thin margin left Kah in fifth, with Ho and Leung sharing the HK$100,000 check for third place.
Leung was only confirmed as a late substitution for Mickael Barzalona and timed his late thrust to perfection when dropping Win Win Fighter in front on the line to deny Hugh Bowman and Royal Pride.
Lor secured the HK$200,000 bonus as leading trainer across the four legs, edging out Tony Cruz and Francis Lui thanks to Adios' win.