Albion boss Sami Hyypia admitted today it's "not ideal" to have gaps still to fill in the squad, with the new season a fortnight away.
The Seagulls are expected to make several more signings before and possibly after Sheffield Wednesday's opening visit on August 9.
Hyypia, speaking following the 2-1 friendly defeat at Peterborough said: "I'm okay. The players are working hard and trying to do the right things. When it's only two weeks before the start of the season I would like the squad to be there for the season.
"That of course is one thing that's not ideal. We haven't got the whole squad together."
The players were allowed a World Cup style water break midway through the first half at a steamy London Road. Hyypia felt the pitch should have been watered as well.
He said: "Today the pitch made it very difficult to play football, because it was dry. I heard that Peterborough are a side that wants to play football and I would have thought they would put some water on it but they didn't. It was a bit of a surprise.
"It wasn't a waste. It was a good workout for the players. Friendly games are the best training sessions you can have."