Tyrone snatched a one-point victory over All-Ireland finalists Mayo thanks to a Stephen O'Neill penalty with virtually the last kick of the match.
Mayo, boosted by a Keith Higgins goal, looked to be on course to win having come from four behind to lead by two points in the Division One clash.
But then Mark Donnelly was fouled from behind when he was in on goal and ref Maurice Deegan awarded the penalty.
Red Hands skipper O'Neill blasted his kick past keeper David Clarke.
That made it two wins out of two for Mickey Harte's men in the league.
"We thought we had lost the game but thankfully Mark got the penalty," said O'Neil.
"We knew it was going to be a battle - it always is here.
"We are delighted to get to the break with four points on the board but we are by no means the finished article."
It was an exciting finish to a closely-contested affair at McHale Park.
Towards the end it looked as if Tyrone might pay for some indiscipline as eight of Mayo's 11 points had come from frees.
Indeed, Mayo had made the better start and led by two, courtesy of Jason Doherty and Lee Keegan.
However, Tyrone settled and two Peter Harte points, a fine Sean Cavanagh free and an O'Neill score edged Tyrone ahead.
The Red Hands' keeper Niall Morgan landed two long-range frees to give the Ulster county a 0-6 to 0-4 interval advantage.
Doherty and Kevin McLaughlin brought the Westerners level early in the second half but Martin Penrose, just on as a sub, and Cathal McCarron added to the Tyrone tally.
Conor McAliskey, Cavanagh, Ronan McNamee and Darren McCurry tagged on more points for the visitors.
McLaughlin added two for Mayo but Tyrone were 0-12 to 0-8 up going into the closing stages.
However, the drama was still to unfold and Mayo were right back in it when Higgins blasted into the roof of the net from Doherty's flick.
Defender Donal Vaughan then advanced to land the point which levelled the contest.
Two frees took Doherty's tally to six points and gave Mayo a two-point lead heading into the additional time.
Then came the O'Neill penalty which saw Tyrone snatch their last-gasp victory.
National League results - Sunday 10 February
Kerry 0-4 1-11 Dublin
Mayo 1-11 1-12 Tyrone
Armagh v Wexford - postponed
Derry 1-17 2-11 Laois
Longford 1-8 2-7 Westmeath
Louth v Galway - postponed
Sligo 1-12 0-13 Antrim
Wicklow 0-8 0-16 Meath
Leitrim 2-8 1-14 Clare
Offaly 1-8 0-12 Limerick