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.

If you are looking to diversify your portfolio, consider AB Value I (ABVIX Quick QuoteABVIX - Free Report) . ABVIX 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. This fund is a winner, boasting an expense ratio of 0.7%, management fee of 0.55%, and a five-year annualized return track record of 10.09%.

MainStay Large Cap Growth I (MLAIX Quick QuoteMLAIX - Free Report) : 0.73% expense ratio and 0.62% management fee. MLAIX 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 17% over the last five years, MLAIX is an effectively diversified fund with a long reputation of solidly positive performance.

T. Rowe Price Mid-Cap Value (TRMCX Quick QuoteTRMCX - Free Report) . Expense ratio: 0.8%. Management fee: 0.64%. Five year annual return: 12.14%. TRMCX is a Mid Cap Value fund, which usually invests in companies with a stock market valuation between $2 billion and $10 billion.

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.