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 Fidelity Fund K (FFDKX Quick QuoteFFDKX - Free Report) . FFDKX is classified as a Large Cap Blend fund. More often than not, Large Cap Blend mutual funds invest in companies with a market cap of over $10 billion. Buying stakes in bigger companies offer these funds more stability, and are well-suited for investors with a "buy and hold" mindset. This fund is a winner, boasting an expense ratio of 0.37%, management fee of 0.32%, and a five-year annualized return track record of 14.03%.

Janus Henserson Forty Institutional (JACAX Quick QuoteJACAX - Free Report) . Expense ratio: 0.55%. Management fee: 0.48%. JACAX 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 14.18% over the last five years.

Matthews Asia Small Companies (MSMLX Quick QuoteMSMLX - Free Report) . Expense ratio: 1.32%. Management fee: 1%. Five year annual return: 14.07%. MSMLX is a Pacific Rim - Equity fund, which usually invest in companies with a big presence in the export-focused markets of Hong Kong, Singapore, Taiwan, and Korea.

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.