It is never too late to invest in mutual funds for retirement. As such, if you plan to invest in some of the best funds, the Zacks Mutual Fund Rank can provide you with valuable guidance.

The easiest, most reliable way to judge a mutual fund's quality over time is by analyzing its performance, diversification, and fees. The Zacks Mutual Fund Rank, which covers over 19,000 mutual funds, has helped us identify three outstanding options that are perfect for any long-term investors' portfolios that is retirement-focused.

Let's break down some of the mutual funds with the top Zacks Mutual Fund Rank and the lowest fees.

Causeway Global Value Investor (CGVVX Quick QuoteCGVVX - Free Report) has a 1.1% expense ratio and 0.8% management fee. CGVVX is a Global - Equity mutual fund. These funds invest in large markets like the U.S., Europe, and Japan, and operate with very few geographical limitations. With yearly returns of 10.25% over the last five years, this fund clearly wins.

Columbia Small Cap Value I Class Z (CSCZX Quick QuoteCSCZX - Free Report) : 1% expense ratio and 0.81% management fee. CSCZX is a Small Cap Value fund, and these funds are known for investing in companies with market caps under $2 billion. CSCZX, with annual returns of 10.6% over the last five years, is a well-diversified fund with a long track record of success.

Fidelity Advisor Energy Fund I (FANIX Quick QuoteFANIX - Free Report) . Expense ratio: 0.73%. Management fee: 0.53%. Five year annual return: 13.54%. FANIX is a Sector - Energy mutual fund, which encompasses a wide range of vastly changing and vitally important industries throughout this massive global sector.

We hope that your investment advisor (if you use one) has you invested in one or all of the top-ranked mutual funds we've reviewed. But if that isn't the case, it might be time to have a conversation or reconsider this vitally important relationship.