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.

If you are looking to diversify your portfolio, consider MassMutual Select Equity Opportunities Service Class (MMFYX Quick QuoteMMFYX - Free Report) . MMFYX is classified as a Large Cap Blend fund. More often than not, Large Cap Blend mutual funds invest in companies with a market cap of over $10 billion. Buying stakes in bigger companies offer these funds more stability, and are well-suited for investors with a "buy and hold" mindset. This fund is a winner, boasting an expense ratio of 0.93%, management fee of 0.69%, and a five-year annualized return track record of 11.34%.

Dreyfus Strategic Value Y (DRGYX Quick QuoteDRGYX - Free Report) : 0.63% expense ratio and 0.6% management fee. DRGYX is a Large Cap Value mutual fund, which invests in stocks with a market cap of $10 billion of more, but whose share prices do not reflect their intrinsic value. DRGYX, with annual returns of 11.2% over the last five years, is a well-diversified fund with a long track record of success.

Fidelity OTC Portfolio K (FOCKX Quick QuoteFOCKX - Free Report) : 0.76% expense ratio and 0.66% management fee. FOCKX is a Large Cap Growth option; these mutual funds purchase stakes in numerous large U.S. companies that are expected to develop and grow at a faster rate than other large-cap stocks. With a five-year annual return of 13.98%, this fund is a well-diversified fund with a long track record of success.

These examples highlight the fact that there are some astonishingly good mutual funds out there. If your advisor has you in the good ones, bravo! If not, you may need to have a talk.