Lambert saw the 18-year-old score twice for Stoke under-23s against Middlesbrough on Monday – taking his tally to the season to 14.
And, while Campbell is still training regularly with his own age group, Lambert will not rule out handing the son of ex-Arsenal and Everton striker Kevin Campbell a first-team call in the not-too-distant future.
The Stoke boss said: “I can’t over-protect him but I don’t want to flog him out there either. This is new to him, this situation, so I’ve got to watch him. I will know myself when the time is right.
“He’s got to earn the right to get in first and foremost, he’s got to earn that, and he has to give me that problem. As an out and out goal scorer, he’ll do that.
“He played on Monday and had a couple of days’ recovery, then he trained with the kids – I had enough bodies just at the minute – but he’s one I will keep monitoring, certainly, because I think he’s got a wee chance.
“His two goals on Monday night were excellent. It’s that one of he probably didn’t do much in the game, in contacts and general link up, but when he came into the box it was bread and butter, that’s a goal scorer. The kid is a natural goal scorer.”
Uwe Rosler was sacked by Fleetwood following a 3-0 reverse at Doncaster which condemned Town to a seventh straight defeat in all competitions.
Cambridge interim head coach Joe Dunne was pleased with how his side adapted to beat Grimsby 3-1.
Southend manager Chris Powell led the applause for Jason Demetriou after the right-back scored twice in the 3-1 win against Portsmouth at Roots Hall.
Morecambe boss Jim Bentley was the happier manager after Gregg Wylde's 90th-minute strike earned his side a point in their 1-1 draw with Forest Green.
Manager Gareth Ainsworth described Wycombe's 2-0 win at Cheltenham as a thoroughly professional performance.
Skipper Richard Wood scored the winner just before half time as in-form Rotherham pulled off a 1-0 victory at League One leaders Shrewsbury.