Now Cobblers wideman Johnson looks set to follow the Australian international into Elland Road.
Leeds agreed a fee for Johnson, believed to be in the region of £250k, and the 20-year-old left winger travelled to United's Thorp Arch training complex for contract talks last night.
The two parties are believed to be in agreement over Johnson's wages and are on the verge of ratifying a long-term deal. Johnson is expected to undergo a medical and sign his contract early next week.
Leeds' discussions with Johnson came less than 24 hours before Northampton were due to line up against them at Elland Road today. Northampton ruled Johnson out of the fixture after accepting their bid for the winger.
However, Johnson also has an offer on the table from a club in the Coca-Cola Championship, and may prefer that to a switch to a team in the same division.