Sunderland have had a relatively quiet summer, signing only Sebastian Coates, Jeremain Lens and Younes Kaboul with a week of the transfer window remaining.
This is in stark contrast to the six additions under Gus Poyet last year, with 11 coming under Paolo Di Canio a year prior.
The Black Cats, who finished 16th and just three points clear of relegation last season, sit second from bottom this campaign after securing their first point against Swansea on Saturday.
While Advocaat was happy with the application of his players at the Stadium of Light, he insists the club need at least two more signings in order to instigate “competition” within the squad.
“If we don’t get players in, then we will have almost the same players as last year,” he is quoted as saying by the Newcastle Chronicle.
“We definitely need players. We need two or three in good positions to get more competition in the squad, that’s important.
“A player can think ‘It doesn’t matter how I play, I will play next week’, so you need competition in the games, but also in training so they don’t feel it is easy. For some it is easy.
“I was happy with how the players played (against Swansea). The only weak point is they cannot do that every week. Sometimes you have to do it with skill like Swansea did, but that takes quality.”
Sunderland have been linked with a move for Liverpool striker Fabio Borini throughout the summer, while reports of a move for Napoli midfielder Jonathan de Guzman emerged over the weekend.