Linfield stretched their unbeaten run in the league to 15 matches as goals by Michael Gault and Michael McAllister earned victory over Portadown.
Skipper Gault stroke home in first-half stoppage-time after a free-kick had only been half cleared by the Ports.
The second came in the 77th minute when McAllister touched the ball goalwards and keeper David Miskelly's attempted clearance went in off the striker.
Portadown had an early setback when striker Gary Twigg went off injured.
Ronnie McFall's men could have taken the lead on 20 minutes but home defender Jim Ervin cleared Keith O'Hara's header off the line from a Ross Redman corner.
Linfield are now level on points with second-placed Crusaders who have slight better goal difference.
Portadown stay seventh but the defeat is a blow to their chances of getting into the top six before the 23 March split as they are seven points behind Ballinamallard United.