The Whites head coach has been impressed with the Brazilian winger in training during the international break, having arrived just 11 days ago from Rennes.
Leeds shelled out around £17m for the 23-year-old and Bielsa is grateful to director of football Victor Orta for bringing a player so suited to the way Leeds play football.
Expectant Leeds fans could get their first sight of the new man on Monday.
"It's difficult to say [if he will be involved on Monday] three days before the game because in three days many things can happen," said the Argentine.
"If the game was today he would be in the group. His adaptation has been very quick, instant. For this I thank Victor Orta as he's a player who is able to adapt very easily to the style of play that we have."
Raphinha's versatility means Bielsa considers him cover and competition for both Jack Harrison on the left wing and Helder Costa on the right. But in time he will also give the head coach another option in the centre.
"He is an additional alternative for the right wing position, left wing position and eventually the central offensive position," said Bielsa.
"Fundamentally he is a winger who can play on the right or left hand side."
His arrival was Leeds' final acquisition of a summer transfer window that has left Bielsa more than satisfied with the players at his disposal.
The addition of Spanish internationals Rodrigo and Diego Llorente, along with Raphinha and German national team defender Robin Koch, gave Leeds the quality they were looking for.
"Totally satisfied," said Bielsa.
"I'm very grateful for the work of Victor Orta and also the group that helps him. I also value the contribution of the club, the president as we were able to incorporate the players we needed.
"They were of a high level, we're very happy."
Even the breakdown of midfielder Michael Cuisance's move to Elland Road at the last minute failed to dampen Bielsa's enthusiasm for the make-up of his squad. He believes he has ample options for each of the midfield positions and hinted that, like Raphinha, Llorente could feature in an alternative role to his traditional central defensive position at some point in the future.
"In the position of attacking midfield we have Pablo [Hernandez], Tyler [Roberts] and Rodrigo who can play there," he said.
"In the position of defensive midfield we have [Kalvin] Phillips, Pascal [Struijk] and [Robin] Koch and eventually [Diego] Llorente as well. In the position of box to box midfielder we have Klich, Dallas, Shackleton and Alioski can play there. These are the options I see."