diff --git a/pytorch_lightning/trainer/training_loop.py b/pytorch_lightning/trainer/training_loop.py
index 6cc2ac55c5..5613f86342 100644
--- a/pytorch_lightning/trainer/training_loop.py
+++ b/pytorch_lightning/trainer/training_loop.py
@@ -319,6 +319,12 @@ class TrainerTrainLoopMixin(ABC):
         # get model
         model = self.get_model()
 
+        # enable train mode
+        model.train()
+
+        # enable gradients
+        torch.set_grad_enabled(True)
+
         # load data
         # if reload_dataloaders_every_epoch, this is moved to the epoch loop
         if not self.reload_dataloaders_every_epoch: