James Forrest hit a double on his first start for five months as Celtic maintained their lead at the top of the cinch Premiership with a 2-1 victory at Dundee.Forrest was drafted in for only his fourth start of the season after coming off the bench to net in last weekend's Scottish Cup semi-final win over Aberdeen.Such was Forrest’s influence at Hampden that manager Brendan Rodgers admitted he might have underused the 32-year-old this season.And his feeling could only have grown as the winger stole the show at Dens Park to take his season tally to six goals.Forrest volleyed home a powerful strike from 18 yards on the half-hour mark and started and finished the move that doubled the lead midway through the second half.The victory swiftly restored Celtic’s three-point lead following Rangers’ 2-1 win at St Mirren in the early kick-off, although their goal difference advantage stayed at five after substitute Adam Idah sliced the ball into his own net as he tried to clear Antonio Portales’ shot.Celtic had scored 26 goals in their previous six meetings with Dundee, half of the tally coming this season, but the champions would have been satisfied to maintain the status quo at the top of the table after some late pressure, during which visiting goalkeeper Joe Hart was booked for time-wasting.Forrest was involved from the opening moments, working room to shoot wide from long range, and Nicolas Kuhn was also cutting in to good effect from the right wing, forcing two saves from Jon McCracken.The Dundee goalkeeper pulled off a better stop from Greg Taylor’s close-range header after Liam Scales had headed on a corner.Reo Hatate then stabbed wide from close range after brilliant wing play from Forrest.Dundee had a brief spell of