The Nationals placed first baseman Nick Johnson on the 15-day disabled list after Sunday's game with a right heel contusion. Johnson has missed six straight games with the injury. The move was retroactive to June 27, one day after he injured his heel while crossing home plate against Toronto. The oft-injured Johnson has been on the disabled list seven times, including twice last year in his first season in the NL after being acquired from the Yankees. Johnson is hitting .320 with eight home runs and leads the Nationals with 42 RBI in 74 games. He played in only 73 games last season for the Expos.