diff --git a/addons/sale/models/sale.py b/addons/sale/models/sale.py
index 660f621ff7e..cc06fbddf41 100644
--- a/addons/sale/models/sale.py
+++ b/addons/sale/models/sale.py
@@ -516,6 +516,9 @@ class SaleOrder(models.Model):
         invoices_origin = {}
         invoices_name = {}
 
+        # Keep track of the sequences of the lines
+        # To keep lines under their section
+        inv_line_sequence = 0
         for order in self:
             group_key = order.id if grouped else (order.partner_invoice_id.id, order.currency_id.id)
 
@@ -524,6 +527,7 @@ class SaleOrder(models.Model):
 
             # Create lines in batch to avoid performance problems
             line_vals_list = []
+            # sequence is the natural order of order_lines
             for line in order.order_line:
                 if line.display_type == 'line_section':
                     pending_section = line
@@ -545,14 +549,21 @@ class SaleOrder(models.Model):
 
                 if line.qty_to_invoice > 0 or (line.qty_to_invoice < 0 and final):
                     if pending_section:
-                        line_vals_list.extend(pending_section.invoice_line_create_vals(
+                        section_invoice = pending_section.invoice_line_create_vals(
                             invoices[group_key].id,
                             pending_section.qty_to_invoice
-                        ))
+                        )
+                        inv_line_sequence += 1
+                        section_invoice[0]['sequence'] = inv_line_sequence
+                        line_vals_list.extend(section_invoice)
                         pending_section = None
-                    line_vals_list.extend(line.invoice_line_create_vals(
+
+                    inv_line_sequence += 1
+                    inv_line = line.invoice_line_create_vals(
                         invoices[group_key].id, line.qty_to_invoice
-                    ))
+                    )
+                    inv_line[0]['sequence'] = inv_line_sequence
+                    line_vals_list.extend(inv_line)
 
             if references.get(invoices.get(group_key)):
                 if order not in references[invoices[group_key]]: