Leicester look set to secure the Premiership top spot for the first time since 2011 after victory at Newcastle.
Nemani Nadolo's early try and a George Ford penalty were the difference as both sides had two first-half scores disallowed after television replays.
George McGuigan's try got Falcons on the board before Ford put Tigers further ahead.
Guy Porter's superb sidestep and a third try from Freddie Steward sealed the success late on.
The result means Leicester have a three-point lead with one game left to play. After beating Northampton 42-38, second-placed Saracens need to win at Gloucester - and hope the Tigers lose at home to Wasps - if they are to snatch first place.
The game marked the final match at Kingston Park for Newcastle boss Dean Richards, who will end his 10-year tenure at the club next week.
The game was marred by a serious-looking injury to Leicester's England hooker Nic Dolly after 30 minutes.
Dolly was taken out by a crocodile roll from Adam Brocklebank and appeared to hurt his ankle, with the Falcons forward yellow-carded for the offence.
The Tigers had started strongly - Chris Ashton had a first-minute try ruled out after replays showed he had stepped into touch - before Nadolo powered his way over from close range 14 minutes later.
Ford's penalty made it 10-0 before Ellis Genge had a try ruled out with no evidence of a grounding after crashing through.
But the Falcons - in front of their biggest home crowd in more than three years - fought back when back up to 15 men. They had two close-range tries ruled out in the space of a minute towards the end of the half following some sustained pressure on the Leicester line.
They did trouble the scorers nine minutes after the restart when McGuigan, who had a try ruled out out before the break, went over from five metres.
But Porter's bit of skill after the ball was swung wide with 10 minutes to go gave Tigers breathing space, before he sent over an excellent cross-field kick which bounced nicely for Steward, who made no mistake.
Newcastle head coach Dave Walder told BBC Radio Newcastle:
"We felt we were in the fight. We fell away a little bit because of the effort we put into the first 65 [minutes].
"We spoke before the game about the boys who are leaving, not making it specifically about them but about doing them proud, and I thought to a man we did that today.
"We got held up over the line twice, the cameras weren't in our favour. Our lads are sure they scored them but that is the way it goes."
Leicester head coach Steve Borthwick told BBC Radio Leicester:
"It was a tough game, I thought Newcastle Falcons played very, very well. We knew we were going to have to work for 80 minutes to get the win we wanted.
"We started that first 20 really well, we didn't get scores in the period and what Newcastle did just before - and just after half-time - was very good, they put us under an enormous amount of pressure.
"What I was really pleased with was after that pressure we came back and I thought we played really well in the last 30."
Newcastle Falcons: Tait; Radwan, Orlando, Burrell, Carreras; Hodgson; Young; Brocklebank, McGuigan, Davison; Peterson, Van der Walt; Graham, Basham, Chick (c).
Replacements: Blamire, Mulipola, Tampin, Lockwood, Fearns, Nordli-Kelemeti, Haydon-Wood, Stephens.
Leicester Tigers: Steward; Ashton, Moroni, Porter, Nadolo; Ford, Wigglesworth; Genge (c), Dolly, Cole; Chessum, Wells; Martin, Liebenberg, Wiese.
Replacements: Clare, Leatigaga, Heyes, Henderson, Reffell, Van Poortvliet, Burns, Scott.
Referee: Anthony Woodthorpe