As morning came without further problems, Nuno Álvares at once gave orders for the trumpets to be sounded and left with all his men for Fronteira, which lay 4 leagues away and was where the Castilians would be heading. On the way he sent a number of his light horsemen ahead to seek news as to where the enemy lay.

At this point, little time passed before a Castilian squire, Ruy González by name, who had formerly lived alongside Nuno Álvares in his father's household and was at this time living in the household of Pedro Álvares his brother, arrived at speed on horseback, heading for Fronteira. He went up to Nuno Álvares, who received him very well and inquired of him the whereabouts of his brother and the other great lords from Castile. His answer was that they were already at Fronteira, which lay about a league and a half away from where he had encountered Nuno Álvares. The latter asked him what they were doing and received the answer that they were planning to attack the town. Urging him to tell the truth, Nuno Álvares then asked him what his purpose was in coming, whether he was a spy or whether he bore a message and, if so, from whom. Ruy González answered him as follows: ‘Lord Nuno Álvares, you are well aware that in this matter, just as in any other, I will never tell you anything but the truth. You can be sure that your brother and the great lords and forces of Castile have been informed that you were equipped and ready to seek them out and do battle with them. They are so surprised at this that they find it very difficult to believe, when you have so few troops as they know you have and yet are engaged in bringing it about. They have asked your brother for his opinion, but his answer was that he did not know, though he could assure them of one thing: if you had begun to do something in this regard, he knew you well enough to say that you would go ahead with it even unto death. The other great lords then requested him to send me to you to find out what your plans were, and that is why I am here.