Investing in mutual funds for retirement is never too late. And the Zacks Mutual Fund Rank can be an excellent tool for investors looking to invest in the best funds.

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.

Here are the funds that have achieved the Zacks Mutual Fund Rank #1 (Strong Buy) and have low fees.

If you are looking to diversify your portfolio, consider Congress Large Cap Growth Fund (CAMLX Quick QuoteCAMLX - Free Report) . CAMLX 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. This fund is a winner, boasting an expense ratio of 0.93%, management fee of 0.5%, and a five-year annualized return track record of 11.65%.

BNY Mellon Natural Resources I (DLDRX Quick QuoteDLDRX - Free Report) : 0.91% expense ratio and 0.75% management fee. DLDRX is classified as a Sector - Energy mutual fund. Throughout the massive global energy sector, these funds hold a wide range of quickly changing and vitally important industries. DLDRX, with annual returns of 15.46% over the last five years, is a well-diversified fund with a long track record of success.

Oppenheimer Discovery R (ODINX Quick QuoteODINX - Free Report) . Expense ratio: 1.26%. Management fee: 0.59%. Five year annual return: 11.26%. ODINX is a Small Cap Growth mutual fund and tends to feature small companies in up-and-coming industries and markets.

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.