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.

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

American Century Large Company Value R6 (ALVDX Quick QuoteALVDX - Free Report) : 0.49% expense ratio and 0.48% management fee. ALVDX 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. ALVDX has achieved five-year annual returns of an astounding 12.63%.

Brandes International Small Cap Equity A (BISAX): 1.32% expense ratio and 0.95% management fee. BISAX is a Non US - Equity fund. Many of these funds like to allocate across emerging and developed markets, and will often focus on all cap levels. With yearly returns of 25.89% over the last five years, BISAX is an effectively diversified fund with a long reputation of solidly positive performance.

Vanguard Small-Cap Value Index Investor (VISVX) is an attractive large-cap allocation. VISVX is a Small Cap Value mutual fund option, which typically invest in companies with market caps under $2 billion. VISVX has an expense ratio of 0.19%, management fee of 0.18%, and annual returns of 14.69% over the past five years.

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.