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 easiest way to judge a mutual fund's quality over time is by analyzing its performance, diversification, and fees. Using the Zacks Mutual Fund Rank of over 19,000 mutual funds, we've identified three outstanding mutual funds that are ideally suited to help long-term investors pursue and achieve their retirement investing goals.

Let's break down some of the mutual funds with the top Zacks Mutual Fund Rank and the lowest fees.

Athena Value I (ATVIX Quick QuoteATVIX - Free Report) : 1.25% expense ratio and 1% management fee. ATVIX is a Mid Cap Value fund, which usually invests in companies with a stock market valuation between $2 billion and $10 billion. ATVIX has achieved five-year annual returns of an astounding 11.62%.

Nationwide Global Sustain Equity A (GGEAX Quick QuoteGGEAX - Free Report) : 1.25% expense ratio and 0.75% management fee. GGEAX is a Global - Equity mutual fund investing in bigger markets like the U.S., Europe, and Japan; these kinds of funds aren't limited by geography. GGEAX, with annual returns of 13.33% over the last five years, is a well-diversified fund with a long track record of success.

Janus Henderson Research I (JRAIX Quick QuoteJRAIX - Free Report) : 0.57% expense ratio and 0.5% management fee. JRAIX 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. The fund is mainly invested in equities, has a long reputation of salutary performance, and has yearly returns of 16.82% 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.