Derek Adams says Sunderland 'have got to be careful' after their 2-0 win at Home Park on Saturday.
The Black Cats have climbed into the automatic places, now just three points behind Portsmouth with a game in hand.
But Adams says his Plymouth side 'were the better team' and deserved to get something from the game.
"I think over the 90 minutes we were the better team. We had double the opportunities on goal that Sunderland had," Adams said.
"Their goalkeeper (Jon McLaughlin) has had a man-of-the-match display and we were against a team that has a lot of talent.
"We went toe to toe with them. They scored a goal just after half-time and got a penalty that we thought was soft.
"We had a couple of claims for penalty kicks that we didn’t get. In the end, we feel hard done to today.
"I don’t think a defeat is the right scoreline. Sunderland rode their luck a number of times in the match.
"They have come away with a scoreline that we probably don’t deserve," Adams added.
"Last week Southend had more opportunities than Sunderland did and Sunderland won.
"Today, we have had more opportunities than Sunderland, and Sunderland have won.
"I’m not sure they are going to get it all their own way this season. I think that they have got to be careful.
"They are obviously the favourites for the league because of the amount of money they have at their disposal, compared to everybody else in this league.
"We obviously had the fifth lowest budget in the league last year. That’s public knowledge and we have competed again very well this season."
Sunderland boss Jack Ross said he was pleased with the way his team controlled the majority of the game.
"I thought with the exception of the 15-20 minute period in the second half when we lost control a bit that it was maybe as good as we have played away from home in terms of dominating the game," Ross said.
"We started second half brightly and got the rewards through Aiden's goal.
"First half we were good, I couldn't have too much criticism. They defended their box well, the later part of the first half.
"We got a bit impatient and narrow and forcing things. We have good quality in the wide areas so we needed to exploit that and to the players credit, they did that."