It is never too late to invest in mutual funds for retirement. As such, if you plan to invest in some of the best funds, the Zacks Mutual Fund Rank can provide you with valuable guidance.

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.

AB Lg Cap Growth Z (APGZX Quick QuoteAPGZX - Free Report) has a 0.51% expense ratio and 0.48% management fee. APGZX 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 11.66% over the last five years, this fund clearly wins.

Principal Capital Appreciation R4 (PCAPX Quick QuotePCAPX - Free Report) is a stand out amongst its peers. PCAPX is a Large Cap Blend fund, targeting companies with market caps of over $10 billion. These funds offer investors a stability, and are perfect for people with a "buy and hold" mindset. With five-year annualized performance of 10.18%, expense ratio of 0.82% and management fee of 0.44%, this diversified fund is an attractive buy with a strong history of performance.

Fidelity Select Technology (FSPTX Quick QuoteFSPTX - Free Report) . Expense ratio: 0.69%. Management fee: 0.53%. Five year annual return: 15.86%. With a much more diversified approach, FSPTX--part of the Sector - Tech mutual fund category--gives investors a way to own a stake in the notoriously risky tech sector.

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.