The Tigers splashed a combined £14million to bring the strikers in from Everton and West Brom in January and have been rewarded with immediate results.
The pair have forged an instant relationship up front and have shared five goals in the five games they have started in tandem.
Both players were cup-tied for Monday night's FA Cup fifth-round win over Brighton but will return for Newcastle's visit to the KC Stadium on Saturday.
Hull were 3-2 winners at St James' Park in the reverse fixture in September, but that was the only occasion they scored more than one goal in their first 12 league outings.
They thrashed Cardiff 4-0 last time out, Jelavic scoring twice and Long proving an ideal foil, and Bruce is enthused by his side's new cutting edge.
"I'd love to say it's all in the training but they're two very good players playing together," he said.
"There's a lot said about coaching but a good player is a good player and in management the more of them you've got the easier it becomes.
"They came in at just the right time and all of a sudden we're a different animal up front.
"That's no disrespect to what we had before but at the end of the day they're two ?6million players and you'd expect that
We're delighted we've got them and I think they're a terrific partnership.
"That's what you invest in, they give you that little something you'd didn't have before."
Paul McShane (ankle) and Robbie Brady (groin) are the only long-term absentees for the Tigers and are unlikely to be seen again this season.
Hatem Ben Arfa (knock) and Davide Santon (knee) will be missing from the Newcastle squad.
Newcastle boss Alan Pardew is backing Cheick Tiote to help fill the void left by Yohan Cabaye after seeing him grow in stature in the wake of the Frenchman's departure.
The Magpies lost their influential playmaker in January when France international Cabaye headed for Paris St Germain in exchange for a cheque for more than B#19million.
His exit coincided with a dreadful run of results for Pardew's men which saw their hopes of securing a top-six Barclays Premier League finish dwindle.
However, they bounced back with a vital 1-0 victory over Aston Villa last Saturday, and while Tiote may have played the role of artisan alongside Cabaye's artistry, his manager believes his leadership qualities are coming to the fore.
Pardew said: "He is an important player to us, and the captaincy when Colo (Fabricio Coloccini) was out changed him a little bit.
"He knows now that in my mind, he is our vice-captain and he has to play the role that that involves.
"It's a big club, so he has a lot of responsibility and he's dealing with it very well
In fact, it's spurred him on."
At the KC Stadium the Magpies will attempt to gain revenge for the 3-2 home defeat they suffered at the hands of the Tigers in September.
However, Pardew is well aware of how difficult a task that could be with Bruce's promoted side sitting in 11th place on 30 points and with their destiny in their own hands.
The 52-year-old said: "With my League Managers' Association hat on, I have to say that Steve Bruce, up until this point, is probably manager of the year, although he's got another 11 games to see that over the line.
"But what he did last year with 10 games to go to get them promoted, and to get them into the position they have been in is a fantastic achievement, and he and his staff can be very proud of what they have done."
Source : PA
Source: PA