The Saints suffered a narrow 1-0 defeat to Palace away from home at Selhurst Park in the Premier League.
France international midfielder Yohan Cabaye’s goal in the 38th minute proved to be the difference between the two teams in London.
Koeman has taken to Twitter to give his reaction to the Saints’ defeat, claiming that his team were unlucky.
Today we worked hard in difficult conditions, with strong winds! Allthough we did have opportunities to score, we were unlucky.— Ronald Koeman (@RonaldKoeman) December 12, 2015
Over the course of the 90 minutes at Selhurst Park, hosts Palace had 43% of the possession, took 12 shots of which five were on target, and earned eight corners.
Visitors Southampton had 57% of the possession, took 15 shots of which just three were on target, and earned five corners.
The Saints are now 12th in the Premier League table with 21 points from 16 matches.