diff --git a/src/sitemap/handler.js b/src/sitemap/handler.js
index a3b6d002..d7232c03 100644
--- a/src/sitemap/handler.js
+++ b/src/sitemap/handler.js
@@ -190,34 +190,42 @@ export async function getBaseUrlPagesFromSitemaps(baseUrl, urls) {
   const baseUrlVariant = toggleWWW(baseUrl);
   const contentsCache = {};
 
-  // Prepare all promises for checking each sitemap URL.
-  const checkPromises = urls.map(async (url) => {
+  const fillSitemapContents = async (url) => {
     const urlData = await checkSitemap(url);
     contentsCache[url] = urlData;
     return { url, urlData };
-  });
+  };
+
+  // Prepare all promises for checking each sitemap URL.
+  const checkPromises = urls.map(fillSitemapContents);
 
   // Execute all checks concurrently.
   const results = await Promise.all(checkPromises);
   const matchingUrls = [];
 
   // Process each result.
-  results.forEach(({ url, urlData }) => {
+  for (const { url, urlData } of results) {
     if (urlData.existsAndIsValid) {
       if (urlData.details && urlData.details.isSitemapIndex) {
         console.log(`Sitemap Index found: ${url}`);
         const extractedSitemaps = getSitemapUrlsFromSitemapIndex(urlData.details.sitemapContent);
         console.log(`Extracted Sitemaps from Index: ${extractedSitemaps}`);
-        extractedSitemaps.forEach((extractedSitemapUrl) => {
+        for (const extractedSitemapUrl of extractedSitemaps) {
           if (!contentsCache[extractedSitemapUrl]) {
             matchingUrls.push(extractedSitemapUrl);
+            try {
+              // eslint-disable-next-line no-await-in-loop
+              await fillSitemapContents(extractedSitemapUrl);
+            } catch (err) {
+              // not available
+            }
           }
-        });
+        }
       } else if (url.startsWith(baseUrl) || url.startsWith(baseUrlVariant)) {
         matchingUrls.push(url);
       }
     }
-  });
+  }
 
   console.log(`Matching URLs for further processing: ${matchingUrls}`);
 
diff --git a/test/audits/sitemap.test.js b/test/audits/sitemap.test.js
index 1bf1e5dc..7d349429 100644
--- a/test/audits/sitemap.test.js
+++ b/test/audits/sitemap.test.js
@@ -65,7 +65,14 @@ describe('Sitemap Audit', () => {
     + `<sitemap><loc>${url}/sitemap_bar.xml</loc></sitemap>\n`
     + '</sitemapindex>';
 
+  const payload1 = '<?xml version="1.0" encoding="UTF-8"?>\n'
+    + '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">\n'
+  + `<url> <loc>${url}/foo</loc></url>\n`
+  + `<url> <loc>${url}/bar</loc></url>\n`
+  + '</urlset>';
+
   beforeEach('setup', () => {
+    nock.cleanAll();
     context = new MockContextBuilder()
       .withSandbox(sandbox)
       .build(message);
@@ -132,7 +139,7 @@ describe('Sitemap Audit', () => {
       });
     });
 
-    it.skip('runs successfully for sitemap extracted from robots.txt through sitemap index', async () => {
+    it('runs successfully for sitemap extracted from robots.txt through sitemap index', async () => {
       nock(url)
         .get('/robots.txt')
         .reply(200, `Sitemap: ${url}/sitemap_index.xml`);
@@ -142,11 +149,11 @@ describe('Sitemap Audit', () => {
         .reply(200, sitemapIndex);
 
       nock(url)
-        .head('/sitemap_foo.xml')
-        .reply(200);
+        .get('/sitemap_foo.xml')
+        .reply(200, payload1);
 
       nock(url)
-        .head('/sitemap_bar.xml')
+        .get('/sitemap_bar.xml')
         .reply(200);
 
       nock(url)
@@ -574,7 +581,7 @@ describe('Sitemap Audit', () => {
       });
     });
 
-    it.skip('should return success when sitemap_index.xml is found', async () => {
+    it('should return success when sitemap_index.xml is found', async () => {
       nock(url)
         .get('/robots.txt')
         .reply(200, 'Allow: /');