Johnson will start Tuesday's game against the Nationals, Chris Cotillo of MassLive.com reports.
Johnson went four innings as a fill-in starter for Steven Wright (knee) last Thursday, and manager Alex Cora feels the left-hander could get up to five innings Tuesday. This could be the last start for Johnson with Drew Pomeranz (biceps) nearing a return. He owns a 4.28 ERA and 7.9 K/9 in 40 innings for Boston on the season.