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 best way to shortlist great mutual funds is to ensure solid performance, diversification, and low fees. Some are better than others, but utilizing the Zacks Mutual Fund Rank, we have identified three mutual funds that could be solid additions to one's retirement portfolio.

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

DFA Large Cap International Institutional (DFALX Quick QuoteDFALX - Free Report) : 0.17% expense ratio and 0.14% management fee. DFALX is a Non US - Equity fund. Many of these funds like to allocate across emerging and developed markets, and will often focus on all cap levels. With annual returns of 10.34% over the last five years, this fund is a winner.

Emerald Growth Fund Institutional (FGROX): 0.75% expense ratio and 0.61% management fee. FGROX is a Small Cap Growth mutual fund and tends to feature small companies in up-and-coming industries and markets. FGROX, with annual returns of 11.76% over the last five years, is a well-diversified fund with a long track record of success.

Principal Capital Appreciation R3 (PCAOX): 0.99% expense ratio and 0.41% management fee. PCAOX 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. With a five-year annual return of 11.68%, this fund is a well-diversified fund with a long track record of success.

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.