Sheffield fired a warning to their Championship rivals with a 51-42 win over Peterborough at Owlerton.
It was another determined performance from Tigers who kept pressure on the top three in the Championship.
Already without local teenager Jack Parkinson-Blackburn, Sheffield received another blow just hours before the meeting when guest replacement Joe Lawlor pulled out of the meeting after picking up a hand injury on the afternoon.
Belle Vue Colts rider Andy Mellish was drafted in last minute but was unable to make an impact in the tier higher than he is used to.
The Tigers took the chequered flag in the opening two heats, but were forced to settle for a share of the spoils in both. Todd Kurtz and Rob Branford were the riders who made the most of two quick starts with Mellish and, uncharacteristically, Grajczonek finishing out at the back.
But Sheffield drew first blood with a 5-1 maximum in the third.
Lasse Bjerre got away with a flyer at the start while Josh Bates rode some clever defensive lines to keep Paul Starke at bay.
Tom Bacon flew out of the start for the visitors in the fourth, but a ruthless move from Tigers skipper Kyle Howarth saw him charge under the Peterborough man on bends three and four of the opening lap to force himself to the front.
But the hosts would extend their advantage thanks to the Bjerre/Bates duo once again in the fifth.
Bjerre made another terrific start while Bates did things the harder way.
The Barnsley-born racer closed his eyes and shot his way through the smallest of gaps, scraping the boards down the back straight to go from last to second and generated a thunderous roar from the Owlerton faithful.
Jack Holder secured Peterborough’s first race win of the night in the sixth, in the first of a run of four shared heats with eight points between the two sides.
After Kurtz hit the front again in the tenth, it was Grajczonek who fired himself up this time around to steam under Peterborough captain Ulrich Ostergaard on the entrance to lap two to extend the advantage to 12 points.
That enabled Three-time British Champion Chris Harris to come out for double points in the twelfth and take six for the win, but crucially Howarth battled his way past Wilson-Dean around the outside mid race to limit the Panthers to a 7-2.
But the Tigers hit back with a heat advantage of their own and when Ostergaard fell for the visitors in the penultimate race, the hosts claimed all three points with a race to spare.
SHEFFIELD 51: Josh Bates 10+2, Lasse Bjerre 10+1, Todd Kurtz 8, Josh Grajczonek 8, Kyle Howarth 8, Rob Branford 7+1, Andy Mellish 0
PETERBOROUGH 42: Chris Harris 13+2, Jack Holder 12+1, Bradley Wilson-Dean 5+1, Paul Starke 5+1, Tom Bacon 3+2, Richard Hall 2, Ulrich Ostergaard 2.