The Black Cats boss has consistently stressed his opinion that Defoe needs a partner if he is to play up top, and has regularly deployed him as a wide-man as a result.
Defoe was utilised in a more central position in Sunderland's last match against Tottenham Hotspur, though, and largely impressed with his display - but Advocaat still believes that he cannot lead the line by himself.
"I put Defoe in that position because we changed the system," he said. “I still think really he is a 4-4-2 player with a targetman who he plays alongside.
“He’s not a lone striker, I keep saying that. But because we changed things with Toivonen in behind him, it’s a different position for Jermain. They can switch. There were some excellent moments from the front four and that has to become better and better.”
Sunderland utilised a 4-2-3-1 system against Spurs, and they put in their best performance of the season to date during the contest.
Although Ryan Mason's late goal stopped them from picking up any points, they still impressed their supporters with their work-rate and attacking quality.
It gives the team something to build on ahead of their fixture away at Bournemouth, which arrives on Saturday.
Sunderland head to the south coast still looking for their first win of the season, after what has been a disappointing opening to the 2015/16 campaign.