diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportPreviewDataFrameAnalyticsAction.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportPreviewDataFrameAnalyticsAction.java
index 40f7fc2cf7a0a..cd2ee3e01c6d4 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportPreviewDataFrameAnalyticsAction.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/action/TransportPreviewDataFrameAnalyticsAction.java
@@ -77,10 +77,10 @@ public TransportPreviewDataFrameAnalyticsAction(
         this.clusterService = clusterService;
     }
 
-    private static Map<String, Object> mergeRow(DataFrameDataExtractor.PreviewRow row, List<String> fieldNames) {
-        return row.getValues() == null
+    private static Map<String, Object> mergeRow(String[] row, List<String> fieldNames) {
+        return row == null
             ? Collections.emptyMap()
-            : IntStream.range(0, row.getValues().length).boxed().collect(Collectors.toMap(fieldNames::get, i -> row.getValues()[i]));
+            : IntStream.range(0, row.length).boxed().collect(Collectors.toMap(fieldNames::get, i -> row[i]));
     }
 
     @Override
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/extractor/DataFrameDataExtractor.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/extractor/DataFrameDataExtractor.java
index 5f70ae503299d..2f1b2297393de 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/extractor/DataFrameDataExtractor.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/extractor/DataFrameDataExtractor.java
@@ -125,7 +125,7 @@ public Optional<SearchHit[]> next() throws IOException {
      * Does no sorting of the results.
      * @param listener To alert with the extracted rows
      */
-    public void preview(ActionListener<List<PreviewRow>> listener) {
+    public void preview(ActionListener<List<String[]>> listener) {
 
         SearchRequestBuilder searchRequestBuilder = new SearchRequestBuilder(client)
             // This ensures the search throws if there are failures and the scroll context gets cleared automatically
@@ -154,10 +154,10 @@ public void preview(ActionListener<List<PreviewRow>> listener) {
                     return;
                 }
 
-                List<PreviewRow> rows = new ArrayList<>(searchResponse.getHits().getHits().length);
+                List<String[]> rows = new ArrayList<>(searchResponse.getHits().getHits().length);
                 for (SearchHit hit : searchResponse.getHits().getHits()) {
                     String[] extractedValues = extractValues(hit);
-                    rows.add(new PreviewRow(extractedValues));
+                    rows.add(extractedValues);
                 }
                 delegate.onResponse(rows);
             })
@@ -433,21 +433,6 @@ public DataSummary(long rows, int cols) {
         }
     }
 
-    public static class PreviewRow {
-
-        @Nullable
-        private final String[] values;
-
-        private PreviewRow(String[] values) {
-            this.values = values;
-        }
-
-        @Nullable
-        public String[] getValues() {
-            return values;
-        }
-    }
-
     public static class Row {
 
         private final SearchHit hit;