The Capital septet never relinquished their lead last night following a 5-1 in the very first heat at Brough Park courtesy of skipper, and No.1 Sam Masters, and Norwegian Lasse Fredriksen.
The visitors produced nine of the 15-heat winners and are now heavy favourites to progress when the Diamonds visit Armadale on Friday for the second leg. The winners will face the Glasgow Tigers in the last eight.
Italian Paco Castagna, who scored six from his four outings, said: "It's nice to be in a team like this because we've all gelled pretty quickly. I'm very happy overall. It's a great win for the team and I think we can do the job at home on Friday.
"I had a good couple of heats so it's a confidence booster. I'm going to spend this week working on my bikes and be ready for this Friday. We can't take Newcastle for granted. Eight points is a really good advantage to have going into the second leg but it will still be tough. They will be out for revenge so I think it is going to be a very hard meeting."
Meanwhile, the Monarchs contested their first away fixture in this season's Championship on Saturday night, going down 56-34 to the Berwick Bandits at Shielfield Park.
The Bandits were beaten 50-40 at Armadale just 24 hours beforehand but were well worth their win on home shale.
The home men were in fine form from the off leaving the Monarchs chasing their tails and insult was added to injury when Josh Pickering came off trying to round the field in the last heat, teammate Paco Castagna the unlucky one as Pickering's bike clattered into him.
Monarchs team manager Alex Harkess said: “The score line was perhaps no great surprise, it's a tough place to come particularly if you haven't been before. I thought we got better as the match went on but by that point we had too much to do.
“As the match gets to the latter stages gate one is impossible and that was our downfall. Sam was excluded when on gate 1 and he feels unfairly as he is made the start and we feel that should have been first bend bunching at worse. Then heat 15 Josh comes off and unfortunately Paco comes off worse so I'm not sure we've got out of the meeting with seven fit riders we'll have to wait and see.”