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.

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

DFA US Small Cap Growth Institutional

(DSCGX Quick QuoteDSCGX - Free Report) : 0.32% expense ratio and 0.28% management fee. DSCGX is a Small Cap Growth mutual fund and tends to feature small companies in up-and-coming industries and markets. DSCGX has achieved five-year annual returns of an astounding 13.02%.

Invesco Gold & Special Minerals A

(OPGSX Quick QuoteOPGSX - Free Report) : 1.1% expense ratio and 0.6% management fee. OPGSX is classified as a Sector - Precious Metal fund, and these mutual funds invest in stocks with a focus on the mining and production of precious metals like gold, silver, platinum, and palladium. OPGSX, with annual returns of 11.32% over the last five years, is a well-diversified fund with a long track record of success.

Principal Mid Cap R1

. Expense ratio: 1.46%. Management fee: 0.58%. Five year annual return: 11.87%. PMSBX is a Mid Cap Growth mutual fund. These mutual funds choose companies with a stock market valuation between $2 billion and $10 billion.

There you have it. If your financial advisor had you put your money into any of our top-ranked funds, then they've got you covered. If not, you may need to talk.