It wasn’t a vintage performance from the Scotsman, who has been under-fire from the north London crowd on previous visits to the oche, but clad in tartan trews and a saltire shirt, he finished with a 136 check-out – despite missing 45 darts when seeking doubles throughout the match.
And after eliminating his Portuguese opponent 4-3 to extend his first trip to the tournament, Soutar gave a nod to his daytime occupation as he set up a meeting with Englishman Callan Rydz in round four.
“I had a thought in my head before I played him, was he going to be Jose or hose-B? And I think it was hose-B I played so it was all good,” he joked with Sky Sports.
“My hands are soaking with sweat and for people back home they don't understand how nerve-racking that is. It is so horrible but when you win the elation and the feeling that you get for Scotland, for me, is amazing.
“I am absolutely buzzing obviously, with a treble 20, treble 20 and finish on a double. I can't hit doubles the rest of the game – but I'll take it, it's amazing.”
Soutar, who joins fellow Scot Peter Wright in the next round, will now face Rydz who stunned Nathan Aspinall in straight sets in his third round encounter.
added: “The last 16 is only another match. Let’s beat whoever is in front of me and whoever wins the next game has to play me, I don't have to play them,” said a defiant Soutar.
Former world champion Gary Anderson will bid to make it three Scots into the last 16 when he faces Ian White on Wednesday evening.
Meanwhile, Gerwyn Price has called for the tournament to be postponed following a coronavirus outbreak at the event.
Dave Chisnall became the latest player to withdraw on Wednesday after testing positive.
The Englishman and world number 14 followed Michael van Gerwen and Vincent van der Voort out of the competition prematurely.
World champion Price wrote on his Instagram Story: "Tournament needs to be postponed".
He later added in a second post: "I've been in their position so I feel for the players that have had to withdraw, there's a lot of hard work gone into getting events like the World Championships on so postponing probably isn't the best option but an option I wouldn't disagree with, time to keep myself safe and out of touch...keep safe all".
Welshman Price, the world number one, is due to play Dirk van Duijvenbode in a fourth-round match on Wednesday evening.
Chisnall was due to play Luke Humphries in the last-32 on Wednesday, with Humphries now receiving a bye.
A statement from the PDC read: "Dave Chisnall has withdrawn from the William Hill World Darts Championship after testing positive for Covid-19 ahead of his match with Luke Humphries.
"Humphries will receive a bye to the last 16 and Wednesday afternoon's session will continue with two matches."
"Jose de Sousa will play Alan Soutar, and Nathan Aspinall then plays Callan Rydz."
Chisnall's withdrawal is another blow for the integrity of the showpiece tournament, with three-time world champion Van Gerwen having pulled out on Tuesday.
Van Gerwen described himself as being "sour" at his withdrawal and called on the PDC to do more.
"They actually have to check everyone at the door every day - they didn't do that," the Dutchman told AD Sportwereld.
"According to the British Government, this is not necessary, but to protect your own organisation and the World Championship, that would have been useful.
"The PDC will at all times say that they have followed the rules of the Government, but they could have been looked at more closely.
"The control has not been strong enough. It is just a big corona bomb now.
"It is as leaky as a basket. Now I pay a high price. I haven't done anything at all - that makes it extra sour."