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, most reliable way to judge a mutual fund's quality over time is by analyzing its performance, diversification, and fees. The Zacks Mutual Fund Rank, which covers over 19,000 mutual funds, has helped us identify three outstanding options that are perfect for any long-term investors' portfolios that is retirement-focused.

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

Brown Advisory Sustainable Growth Investor (BIAWX Quick QuoteBIAWX - Free Report) has a 0.79% expense ratio and 0.53% management fee. BIAWX 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. With yearly returns of 13.95% over the last five years, this fund clearly wins.

Columbia Dividend Income Fund R4 (CVIRX Quick QuoteCVIRX - Free Report) : 0.65% expense ratio and 0.53% management fee. CVIRX 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. With yearly returns of 10.05% over the last five years, CVIRX is an effectively diversified fund with a long reputation of solidly positive performance.

Fidelity Advisor Mega Cap Stock A (FGTAX Quick QuoteFGTAX - Free Report) : 0.9% expense ratio and 0.42% management fee. FGTAX 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 11.62% 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.