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.

Oppenheimer Discovery Y (ODIYX Quick QuoteODIYX - Free Report) : 0.76% expense ratio and 0.59% management fee. ODIYX 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. ODIYX has achieved five-year annual returns of an astounding 13.41%.

Deutsche Capital Growth S (SCGSX Quick QuoteSCGSX - Free Report) . Expense ratio: 0.66%. Management fee: 0.46%. SCGSX 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 has managed to produce a robust 12.64% over the last five years.

Fidelity Advisor Diversified Stock O (FDESX Quick QuoteFDESX - Free Report) : 0.44% expense ratio and 0.4% management fee. FDESX 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 12.04%, 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.