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.

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

Macquarie Asset Strategy R (IASRX Quick QuoteIASRX - Free Report) : 1.36% expense ratio and 0.68% management fee. IASRX is classified as an Allocation Balanced fund, which seeks to invest in a balance of asset types, like stocks, bonds, and cash, and including precious metals or commodities is not unusual. With annual returns of 9.15% over the last five years, this fund is a winner.

Janus Henderson Global Technology S (JATSX): 1.21% expense ratio and 0.64% management fee. JATSX is a Sector - Tech mutual fund, allowing investors to own a stake in a notoriously volatile sector with a much more diversified approach. JATSX, with annual returns of 13.96% over the last five years, is a well-diversified fund with a long track record of success.

Victory Aggressive Growth (USAUX): 0.64% expense ratio and 0.42% management fee. USAUX 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. With a five-year annual return of 13.06%, 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.