The night passed and the sun arose. In the castle of Courtrai the Viscount of Lens waited impatiently to be liberated. Two full days had already passed since the Count of Artois had set up his camp on the Pottelberg hill, and the defender of the castle was in the dark about the plans of the French commander. He sought to point out to Artois how, and along which path, it would be possible to free the garrison rapidly. His soldiers carried a burning torch around the fortress walls to indicate that the Groeninge field was the most suitable place to free the castle. They stopped in front of the Flemish troops, near the Grey Nuns' abbey, and after giving a sign in that direction, they threw down the blazing torches beside the fortress ramparts. Other soldiers in the garrison tried to give signs with their swords, the steel of which shone in the morning sun. They all pointed to the low-lying area that was intersected by the Groeninge and Grote Beek streams and was bounded by the damp Lys marshes and the abbey buildings to the north. To the south the area was bounded by the Courtrai town ramparts. This was the only way left to the Count of Artois to set free the garrison.

The commander saw the signals of the garrison and rode towards the camp of the Flemings on the Groeninge field to take reconnaissance. He realised that he would have to engage in battle and at around 6 o'clock he gave the necessary orders. Trumpets sounded the call to arms, and the French troops were gathered together. The noblemen put on their coats of mail and plates; their horses were harnessed, saddled and completely prepared for battle. The feverish activity on the Pottelberg hill could not fail to escape the attention of the Flemings. On the Groeninge field and in the town of Courtrai the townsmen were called up. They broke down their tents and thousands of soldiers put on their armour, preparing themselves for the approaching battle.