But Warnock still believes the table-toppers can get better.
"We started sluggishly and could have been behind. Portsmouth had a couple of chances they could've done better with, and if they had done, it could've been tough for us.
"We were still a threat, we just weren't solid. We were better in the second half and I think we were the better side. I can feel the lads are getting stronger, we just need to start games more strongly. How many times have we had to come back from a goal behind? We can't keep doing that - not in this division.
"We've had some tough games and have got some tough ones coming up, but I'm enjoying it. The lads are doing well and if they can cut out some mistakes, they'll get even better.
"I'm delighted with the win and another clean sheet. Portsmouth have a great strikeforce and, if they stay fit, they can do some damage in this division during the rest of the season."