May 18, 2009 2:46 PM EST

The Red Sox have been watching Nationals first baseman Nick Johnson, according to a number of team scouts.

Boston could be looking at Johnson as insurance in the event Kevin Youkilis struggles to return from his oblique injury.

Johnson has a very good on-base percentage, something the Red Sox covet, and is in the final year of a three-year deal that will pay him $5.5 million.

Via Boston Globe