The second-placed Feyenoord are currently eight points behind leaders Ajax, but have a good chance of qualifying for Europe thanks to their four-point cushion over PSV, who are fifth.
With the top four teams earning places in the UEFA Champions League and UEFA Europa League, Koeman believes six points can help them avoid the play-offs - contested between teams finishing between fifth and eighth - for the final Europa League place.
"We need two more wins, then we'll probably escape the play-offs," said Koeman.
"But we are obviously going for the best we can achieve which is second place. If we remain focused and are able to continue our good run of recent weeks, we have a good chance of finishing second."
Captain Graziano Pelle returns for Sunday's clash with RKC Waalwijk after serving a four-game suspension for kicking out at the dugout against Twente, and the 51-year-old coach is glad to have the striker back.
"Graziano has shown a great attitude during his suspension," he added. "He has trained well and he has been occupied with the squad behind closed doors.
"The squad have shown that we are good without him, but we're always stronger with Pelle."
Pelle has scored 20 goals in 24 Eredivisie appearances this season.
