There is never a wrong time to invest in mutual funds for retirement. So, if you're still looking for the best mutual funds, the Zacks Mutual Fund Rank can be a great guide.

The best way to shortlist great mutual funds is to ensure solid performance, diversification, and low fees. Some are better than others, but utilizing the Zacks Mutual Fund Rank, we have identified three mutual funds that could be solid additions to one's retirement portfolio.

Let's take a look at some of our top-ranked mutual funds with the lowest fees.

BNY Mellon Natural Resources A (DNLAX Quick QuoteDNLAX - Free Report) : 1.13% expense ratio and 0.75% management fee. DNLAX is a Sector - Energy mutual fund, which encompasses a wide range of vastly changing and vitally important industries throughout this massive global sector. With annual returns of 15.16% over the last five years, this fund is a winner.

MFS Mass Investors Growth Stock R2 (MIRGX Quick QuoteMIRGX - Free Report) . Expense ratio: 0.96%. Management fee: 0.33%. MIRGX 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. This fund has managed to produce a robust 11.98% over the last five years.

Fidelity Select Tech Hardware (FDCPX Quick QuoteFDCPX - Free Report) . Expense ratio: 0.72%. Management fee: 0.53%. Five year annual return: 11.68%. With a much more diversified approach, FDCPX--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.