WASHINGTON — Gary Sheffield is not in the Mets’ lineup again here tonight and appears likely to go on the disabled list Friday if his ailing right hamstring doesn’t show improvement by then.

“He’s still sore,” Jerry Manuel said of the 40-year-old slugger, who has not played since leaving last Friday’s game in Atlanta with what the Mets originally described as cramping in the hamstring.

Sheffield has since revealed that he thinks the cramping and soreness is caused by an electrolyte imbalance.