diff --git a/TTS/tts/models/vits.py b/TTS/tts/models/vits.py
index 364a007b..33aecbf3 100644
--- a/TTS/tts/models/vits.py
+++ b/TTS/tts/models/vits.py
@@ -566,6 +566,7 @@ class Vits(BaseTTS):
 
         self.init_multispeaker(config)
         self.init_multilingual(config)
+        self.init_upsampling()
 
         self.length_scale = self.args.length_scale
         self.noise_scale = self.args.noise_scale
@@ -648,12 +649,6 @@ class Vits(BaseTTS):
                 use_spectral_norm=self.args.use_spectral_norm_disriminator,
             )
 
-        if self.args.encoder_sample_rate:
-            self.interpolate_factor = self.config.audio["sample_rate"] / self.args.encoder_sample_rate
-            self.audio_resampler = torchaudio.transforms.Resample(
-                orig_freq=self.config.audio["sample_rate"], new_freq=self.args.encoder_sample_rate
-            )
-
     def init_multispeaker(self, config: Coqpit):
         """Initialize multi-speaker modules of a model. A model can be trained either with a speaker embedding layer
         or with external `d_vectors` computed from a speaker encoder model.
@@ -734,6 +729,16 @@ class Vits(BaseTTS):
         else:
             self.embedded_language_dim = 0
 
+    def init_upsampling(self):
+        """
+        Initialize upsampling modules of a model.
+        """
+        if self.args.encoder_sample_rate:
+            self.interpolate_factor = self.config.audio["sample_rate"] / self.args.encoder_sample_rate
+            self.audio_resampler = torchaudio.transforms.Resample(
+                orig_freq=self.config.audio["sample_rate"], new_freq=self.args.encoder_sample_rate
+            )
+
     def get_aux_input(self, aux_input: Dict):
         sid, g, lid = self._set_cond_input(aux_input)
         return {"speaker_ids": sid, "style_wav": None, "d_vectors": g, "language_ids": lid}
@@ -831,6 +836,25 @@ class Vits(BaseTTS):
         outputs["loss_duration"] = loss_duration
         return outputs, attn
 
+    def upsampling_z(self, z, slice_ids=None, y_lengths=None, y_mask=None):
+        spec_segment_size = self.spec_segment_size
+        if self.args.encoder_sample_rate:
+            # recompute the slices and spec_segment_size if needed
+            slice_ids = slice_ids * int(self.interpolate_factor) if slice_ids is not None else slice_ids
+            spec_segment_size = spec_segment_size * int(self.interpolate_factor)
+            # interpolate z if needed
+            if self.args.interpolate_z:
+                z = torch.nn.functional.interpolate(
+                    z.unsqueeze(0), scale_factor=[1, self.interpolate_factor], mode="nearest"
+                ).squeeze(0)
+                # recompute the mask if needed
+                if y_lengths is not None and y_mask is not None:
+                    y_mask = (
+                        sequence_mask(y_lengths * self.interpolate_factor, None).to(y_mask.dtype).unsqueeze(1)
+                    )  # [B, 1, T_dec_resampled]
+
+        return z, spec_segment_size, slice_ids, y_mask
+
     def forward(  # pylint: disable=dangerous-default-value
         self,
         x: torch.tensor,
@@ -906,16 +930,8 @@ class Vits(BaseTTS):
         # select a random feature segment for the waveform decoder
         z_slice, slice_ids = rand_segments(z, y_lengths, self.spec_segment_size, let_short_samples=True, pad_short=True)
 
-        if self.args.encoder_sample_rate:
-            slice_ids = slice_ids * int(self.interpolate_factor)
-            spec_segment_size = self.spec_segment_size * int(self.interpolate_factor)
-            if self.args.interpolate_z:
-                z_slice = z_slice.unsqueeze(0)  # pylint: disable=not-callable
-                z_slice = torch.nn.functional.interpolate(
-                    z_slice, scale_factor=[1, self.interpolate_factor], mode="nearest"
-                ).squeeze(0)
-        else:
-            spec_segment_size = self.spec_segment_size
+        # interpolate z if needed
+        z_slice, spec_segment_size, slice_ids, _ = self.upsampling_z(z_slice, slice_ids=slice_ids)
 
         o = self.waveform_decoder(z_slice, g=g)
 
@@ -1029,12 +1045,8 @@ class Vits(BaseTTS):
         z_p = m_p + torch.randn_like(m_p) * torch.exp(logs_p) * self.inference_noise_scale
         z = self.flow(z_p, y_mask, g=g, reverse=True)
 
-        if self.args.encoder_sample_rate and self.args.interpolate_z:
-            z = z.unsqueeze(0)  # pylint: disable=not-callable
-            z = torch.nn.functional.interpolate(z, scale_factor=[1, self.interpolate_factor], mode="nearest").squeeze(0)
-            y_mask = (
-                sequence_mask(y_lengths * self.interpolate_factor, None).to(y_mask.dtype).unsqueeze(1)
-            )  # [B, 1, T_dec_resampled]
+        # upsampling if needed
+        z, _, _, y_mask = self.upsampling_z(z, y_lengths=y_lengths, y_mask=y_mask)
 
         o = self.waveform_decoder((z * y_mask)[:, :, : self.max_inference_len], g=g)