There is never a wrong time to invest in mutual funds for retirement. So, if you're still looking for the best mutual funds, the Zacks Mutual Fund Rank can be a great guide.

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 learn about some of Zacks' highest ranked mutual funds with low fees you may want to consider.

If you are looking to diversify your portfolio, consider Columbia Dividend Income I3 (CDDYX Quick QuoteCDDYX - Free Report) . CDDYX 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. This fund is a winner, boasting an expense ratio of 0.55%, management fee of 0.53%, and a five-year annualized return track record of 10.94%.

Fidelity Advisor Mega Cap Stock A (FGTAX Quick QuoteFGTAX - Free Report) : 0.9% expense ratio and 0.42% management fee. FGTAX is a Large Cap Blend fund, targeting companies with market caps of over $10 billion. These funds offer investors a stability, and are perfect for people with a "buy and hold" mindset. FGTAX, with annual returns of 12.43% over the last five years, is a well-diversified fund with a long track record of success.

T. Rowe Price New Amer Growth I (PNAIX Quick QuotePNAIX - Free Report) is an attractive large-cap allocation. PNAIX is a Large Cap Growth mutual fund, and these funds invest in many large U.S. firms that are projected to grow at a faster rate than their large-cap peers. PNAIX has an expense ratio of 0.66%, management fee of 0.64%, and annual returns of 15.1% over the past five years.

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.