diff --git a/hugolib/site_sections.go b/hugolib/site_sections.go
index 151baac84..891980be2 100644
--- a/hugolib/site_sections.go
+++ b/hugolib/site_sections.go
@@ -154,13 +154,25 @@ func (s *Site) assembleSections() Pages {
 			sect = s.newSectionPage(p.sections[0])
 			sectionPages[sectionKey] = sect
 			newPages = append(newPages, sect)
-		} else if !found {
-			// We don't know what to do with this section yet.
-			undecided = append(undecided, p)
+			found = true
 		}
 
-		pagePath := path.Join(sectionKey, sectPageKey, strconv.Itoa(i))
-		inPages.Insert([]byte(pagePath), p)
+		if len(p.sections) > 1 {
+			// Create the root section if not found.
+			_, rootFound := sectionPages[p.sections[0]]
+			if !rootFound {
+				sect = s.newSectionPage(p.sections[0])
+				sectionPages[p.sections[0]] = sect
+				newPages = append(newPages, sect)
+			}
+		}
+
+		if found {
+			pagePath := path.Join(sectionKey, sectPageKey, strconv.Itoa(i))
+			inPages.Insert([]byte(pagePath), p)
+		} else {
+			undecided = append(undecided, p)
+		}
 	}
 
 	// Create any missing sections in the tree.
@@ -181,17 +193,6 @@ func (s *Site) assembleSections() Pages {
 		}
 	}
 
-	// Create any missing root sections.
-	for _, p := range undecided {
-		sectionKey := p.sections[0]
-		sect, found := sectionPages[sectionKey]
-		if !found {
-			sect = s.newSectionPage(sectionKey)
-			sectionPages[sectionKey] = sect
-			newPages = append(newPages, sect)
-		}
-	}
-
 	for k, sect := range sectionPages {
 		inPages.Insert([]byte(path.Join(k, sectSectKey)), sect)
 		inSections.Insert([]byte(k), sect)
@@ -200,10 +201,20 @@ func (s *Site) assembleSections() Pages {
 	var (
 		currentSection *Page
 		children       Pages
-		rootPages      = inPages.Commit().Root()
 		rootSections   = inSections.Commit().Root()
 	)
 
+	for i, p := range undecided {
+		// Now we can decide where to put this page into the tree.
+		sectionKey := path.Join(p.sections...)
+		_, v, _ := rootSections.LongestPrefix([]byte(sectionKey))
+		sect := v.(*Page)
+		pagePath := path.Join(path.Join(sect.sections...), sectSectKey, "u", strconv.Itoa(i))
+		inPages.Insert([]byte(pagePath), p)
+	}
+
+	var rootPages = inPages.Commit().Root()
+
 	rootPages.Walk(func(path []byte, v interface{}) bool {
 		p := v.(*Page)
 
diff --git a/hugolib/site_sections_test.go b/hugolib/site_sections_test.go
index 78cf7eca4..4617c8fb3 100644
--- a/hugolib/site_sections_test.go
+++ b/hugolib/site_sections_test.go
@@ -58,6 +58,11 @@ Content
 			fmt.Sprintf(pageTemplate, 1, level1))
 	}
 
+	// Issue #3586
+	writeSource(t, fs, filepath.Join("content", "post", "0000.md"), fmt.Sprintf(pageTemplate, 1, 2))
+	writeSource(t, fs, filepath.Join("content", "post", "0000", "0001.md"), fmt.Sprintf(pageTemplate, 1, 3))
+	writeSource(t, fs, filepath.Join("content", "elsewhere", "0003.md"), fmt.Sprintf(pageTemplate, 1, 4))
+
 	// Empty nested section, i.e. no regular content pages.
 	writeSource(t, fs, filepath.Join("content", "empty1", "b", "c", "_index.md"), fmt.Sprintf(pageTemplate, 33, -1))
 	// Index content file a the end and in the middle.
@@ -109,12 +114,24 @@ PAG|{{ .Title }}|{{ $sect.InSection . }}
 	cfg.Set("paginate", 2)
 
 	s := buildSingleSite(t, deps.DepsCfg{Fs: fs, Cfg: cfg}, BuildCfg{})
-	require.Len(t, s.RegularPages, 18)
+	require.Len(t, s.RegularPages, 21)
 
 	tests := []struct {
 		sections string
 		verify   func(p *Page)
 	}{
+		{"elsewhere", func(p *Page) {
+			assert.Len(p.Pages, 1)
+			for _, p := range p.Pages {
+				assert.Equal([]string{"elsewhere"}, p.sections)
+			}
+		}},
+		{"post", func(p *Page) {
+			assert.Len(p.Pages, 2)
+			for _, p := range p.Pages {
+				assert.Equal("post", p.Section())
+			}
+		}},
 		{"empty1", func(p *Page) {
 			// > b,c
 			assert.NotNil(p.s.getPage(KindSection, "empty1", "b"))
@@ -228,7 +245,7 @@ PAG|{{ .Title }}|{{ $sect.InSection . }}
 
 	assert.NotNil(home)
 
-	assert.Len(home.Sections(), 7)
+	assert.Len(home.Sections(), 9)
 
 	rootPage := s.getPage(KindPage, "mypage.md")
 	assert.NotNil(rootPage)