Louth clipped Westmeath's wings in Dundalk as the Division 1B leaders lost for the first time in this season's Allianz NFL, going down 1-12 to 0-07.
Westmeath had John Keane and Damien Healy sent off in the second half as their unbeaten run came to an end.
Shane Lennon latched onto Ronan Carroll’s through ball to grab a sixth-minute goal and steer Louth towards a 1-05 to 0-03 half-time lead.
Alan Mangan pointed twice for the visitors in the opening half.
Dessie Dolan hit all four of Westmeath's second half points while JJ Quigley, Peter McGinnity, Christy Grimes, Aaron Hoey and Lennon all found the target for Louth.
A Mangan point and a sweetly hit '45' from Dolan saw the visitors open well in front of a huge crowd at Dowdalshill.
But those score were cancelled out when Carroll picked out the run of Lennon and the Louth full-forward made no mistake to fire his side into a 1-00 to 0-02 lead.
Points from Mark Stanfield, Paddy Kennan and Grimes (free) followed as the Wee County went four points to the delight of the home support.
Mangan boosted Westmeath's tally to three but an electric Louth continued to take their chances at the other end as Darren Clarke and Mark Brennan, whose point attempt had to be tipped over the bar by Westmeath keeper Gary Connaughton, added points for a 1-05 to 0-03 buffer at half-time.
Incredibly, Dolan was the visitors' only scorer in the entire second half – he hit two frees at the start of the half and cracked over the game's final two points when Louth had the two league points in their back pockets.
In between, Keane walked for his second bookable offence, while Healy followed just a few moments later when he threw a punch at his marker and earned a straight red.
