diff --git a/pkg/stanza/fileconsumer/matcher/matcher.go b/pkg/stanza/fileconsumer/matcher/matcher.go
index a4ce674c2a84..0377bfab3a61 100644
--- a/pkg/stanza/fileconsumer/matcher/matcher.go
+++ b/pkg/stanza/fileconsumer/matcher/matcher.go
@@ -81,6 +81,14 @@ func New(c Criteria) (*Matcher, error) {
 		m.filterOpts = append(m.filterOpts, filter.ExcludeOlderThan(c.ExcludeOlderThan))
 	}
 
+	if c.OrderingCriteria.GroupBy != "" {
+		r, err := regexp.Compile(c.OrderingCriteria.GroupBy)
+		if err != nil {
+			return nil, fmt.Errorf("compile group_by regex: %w", err)
+		}
+		m.groupBy = r
+	}
+
 	if len(c.OrderingCriteria.SortBy) == 0 {
 		return m, nil
 	}
@@ -93,14 +101,6 @@ func New(c Criteria) (*Matcher, error) {
 		c.OrderingCriteria.TopN = defaultOrderingCriteriaTopN
 	}
 
-	if c.OrderingCriteria.GroupBy != "" {
-		r, err := regexp.Compile(c.OrderingCriteria.GroupBy)
-		if err != nil {
-			return nil, fmt.Errorf("compile group_by regex: %w", err)
-		}
-		m.groupBy = r
-	}
-
 	if orderingCriteriaNeedsRegex(c.OrderingCriteria.SortBy) {
 		if c.OrderingCriteria.Regex == "" {
 			return nil, fmt.Errorf("'regex' must be specified when 'sort_by' is specified")
@@ -197,8 +197,8 @@ func (m Matcher) MatchFiles() ([]string, error) {
 	}
 
 	var result []string
-	for _, files := range groups {
-		groupResult, err := filter.Filter(files, m.regex, m.filterOpts...)
+	for _, groupedFiles := range groups {
+		groupResult, err := filter.Filter(groupedFiles, m.regex, m.filterOpts...)
 		if len(groupResult) == 0 {
 			return groupResult, errors.Join(err, errs)
 		}
diff --git a/pkg/stanza/fileconsumer/matcher/matcher_test.go b/pkg/stanza/fileconsumer/matcher/matcher_test.go
index 9b078cac35e5..e95c9d07cda4 100644
--- a/pkg/stanza/fileconsumer/matcher/matcher_test.go
+++ b/pkg/stanza/fileconsumer/matcher/matcher_test.go
@@ -69,6 +69,15 @@ func TestNew(t *testing.T) {
 			},
 			expectedErr: "exclude: parse glob: syntax error in pattern",
 		},
+		{
+			name: "GroupBy",
+			criteria: Criteria{
+				Include: []string{"*.log"},
+				OrderingCriteria: OrderingCriteria{
+					GroupBy: "[a-z]",
+				},
+			},
+		},
 		{
 			name: "RegexEmpty",
 			criteria: Criteria{
@@ -118,6 +127,16 @@ func TestNew(t *testing.T) {
 			},
 			expectedErr: "'top_n' must be a positive integer",
 		},
+		{
+			name: "GroupBy error",
+			criteria: Criteria{
+				Include: []string{"*.log"},
+				OrderingCriteria: OrderingCriteria{
+					GroupBy: "[a-z",
+				},
+			},
+			expectedErr: "compile group_by regex: error parsing regexp: missing closing ]: `[a-z`",
+		},
 		{
 			name: "SortTypeEmpty",
 			criteria: Criteria{
@@ -384,6 +403,43 @@ func TestMatcher(t *testing.T) {
 			},
 			expected: []string{"err.123456789.log"},
 		},
+		{
+			name:    "Numeric Sorting",
+			files:   []string{"err.a.123456788.log", "err.a.123456789.log", "err.a.123456787.log", "err.a.123456786.log", "err.b.123456788.log", "err.b.123456789.log"},
+			include: []string{"err.*.log"},
+			exclude: []string{},
+			filterCriteria: OrderingCriteria{
+				TopN:  6,
+				Regex: `err\.[a-z]\.(?P<value>\d+).*log`,
+				SortBy: []Sort{
+					{
+						SortType:  sortTypeNumeric,
+						RegexKey:  "value",
+						Ascending: false,
+					},
+				},
+			},
+			expected: []string{"err.a.123456789.log", "err.b.123456789.log", "err.a.123456788.log", "err.b.123456788.log", "err.a.123456787.log", "err.a.123456786.log"},
+		},
+		{
+			name:    "Numeric Sorting with grouping",
+			files:   []string{"err.a.123456788.log", "err.a.123456789.log", "err.a.123456787.log", "err.a.123456786.log", "err.b.123456788.log", "err.b.123456789.log"},
+			include: []string{"err.*.log"},
+			exclude: []string{},
+			filterCriteria: OrderingCriteria{
+				TopN:    6,
+				GroupBy: `err\.(?P<value>[a-z]+).[0-9]*.*log`,
+				Regex:   `err\.[a-z]\.(?P<value>\d+).*log`,
+				SortBy: []Sort{
+					{
+						SortType:  sortTypeNumeric,
+						RegexKey:  "value",
+						Ascending: false,
+					},
+				},
+			},
+			expected: []string{"err.a.123456789.log", "err.a.123456788.log", "err.a.123456787.log", "err.a.123456786.log", "err.b.123456789.log", "err.b.123456788.log"},
+		},
 		{
 			name:    "Numeric Sorting Ascending",
 			files:   []string{"err.123456789.log", "err.123456788.log", "err.123456786.log", "err.123456787.log"},
@@ -786,7 +842,7 @@ func TestMatcher(t *testing.T) {
 			} else {
 				assert.NoError(t, err)
 			}
-			assert.ElementsMatch(t, tc.expected, files)
+			assert.Equal(t, tc.expected, files)
 		})
 	}
 }