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.

If you are looking to diversify your portfolio, consider Columbia Seligman Communications and Information Z (CCIZX Quick QuoteCCIZX - Free Report) . With a much more diversified approach, CCIZX--part of the Sector - Tech mutual fund category--gives investors a way to own a stake in the notoriously risky tech sector. This fund is a winner, boasting an expense ratio of 0.9%, management fee of 0.81%, and a five-year annualized return track record of 25.74%.

Goldman Sachs International Tax Managed Equity A (GATMX): 1.21% expense ratio and 0.85% management fee. GATMX is a Non US - Equity option, focusing their investments acoss emerging and developed markets, and can often extend across cap levels too. GATMX, with annual returns of 11.87% over the last five years, is a well-diversified fund with a long track record of success.

AQR Small Cap Multi-Style R6 (QSERX): 0.53% expense ratio and 0.45% management fee. QSERX is a Small Cap Blend mutual fund, allowing investors a way to diversify their funds among various types of small-cap stocks. With a five-year annual return of 12.14%, this fund is a well-diversified fund with a long track record of success.

These examples highlight the fact that there are some astonishingly good mutual funds out there. If your advisor has you in the good ones, bravo! If not, you may need to have a talk.