diff --git a/addons/sale/models/sale_order.py b/addons/sale/models/sale_order.py
index 9f64b5046ad..794dc8f0ffb 100644
--- a/addons/sale/models/sale_order.py
+++ b/addons/sale/models/sale_order.py
@@ -415,9 +415,15 @@ class SaleOrder(models.Model):
     @api.depends('partner_id')
     def _compute_user_id(self):
         for order in self:
-            if order.partner_id and not order.user_id:
-                order.user_id = order.partner_id.user_id or order.partner_id.commercial_partner_id.user_id or \
-                    (self.user_has_groups('sales_team.group_sale_salesman') and self.env.user)
+            if order.partner_id and not (order._origin.id and order.user_id):
+                # Recompute the salesman on partner change
+                #   * if partner is set (is required anyway, so it will be set sooner or later)
+                #   * if the order is not saved or has no salesman already
+                order.user_id = (
+                    order.partner_id.user_id
+                    or order.partner_id.commercial_partner_id.user_id
+                    or (self.user_has_groups('sales_team.group_sale_salesman') and self.env.user)
+                )
 
     @api.depends('partner_id', 'user_id')
     def _compute_team_id(self):