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.

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

Oppenheimer Discovery I

(ODIIX Quick QuoteODIIX - Free Report) . ODIIX is one of many Small Cap Growth mutual funds; these funds tend to create their portfolios around stocks with market capitalization of less than $2 billion. This fund is a winner, boasting an expense ratio of 0.67%, management fee of 0.6%, and a five-year annualized return track record of 11.56%.

T. Rowe Price Mid-Cap Value

(TRMCX Quick QuoteTRMCX - Free Report) is a stand out amongst its peers. TRMCX is a Mid Cap Value mutual funds that aims to target medium-sized companies that possess strong value and income opportunities for investors. With five-year annualized performance of 14.79%, expense ratio of 0.8% and management fee of 0.64%, this diversified fund is an attractive buy with a strong history of performance.

Vanguard Growth & Income Admiral

(VGIAX Quick QuoteVGIAX - Free Report) : 0.24% expense ratio and 0.21% management fee. VGIAX 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. The fund is mainly invested in equities, has a long reputation of salutary performance, and has yearly returns of 15.96% over the last five years.

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.