If you're invested in any of the funds in our "Magnificent Retirement Mutual Funds" list, congratulations on owning some of the best managed and top-performing mutual funds. If you are lucky enough to discover our list of Top-Ranked Funds for the first time, it's never too late to start investing with the best, especially when it comes to your retirement.

The easiest, most reliable way to judge a mutual fund's quality over time is by analyzing its performance, diversification, and fees. Our Zacks Rank 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.

Let's learn about some of Zacks' highest ranked mutual funds with low fees you may want to consider.

Goldman Sachs Strategic Growth R (GSTRX Quick QuoteGSTRX - Free Report) has a 1.39% expense ratio and 0.71% management fee. GSTRX 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 13.85% over the last five years, this fund clearly wins.

Neuberger Berman Mid Cap Growth Investor (NMANX Quick QuoteNMANX - Free Report) . Expense ratio: 0.88%. Management fee: 0.76%. NMANX is a Mid Cap Growth mutual fund. Mid Cap Growth funds pick stocks--usually companies with a market cap between $2 billion and $10 billion--that demonstrate extensive growth opportunities for investors compared to their peers. This fund has managed to produce a robust 10.04% over the last five years.

MSIF International Opportunities IS (MNOPX Quick QuoteMNOPX - Free Report) : 0.91% expense ratio and 0.78% management fee. MNOPX is a Global - Equity mutual fund. These funds invest in large markets like the U.S., Europe, and Japan, and operate with very few geographical limitations. With a five-year annual return of 15.27%, this fund is a well-diversified fund with a long track record of success.

So, there you have it - if your advisor has you invested in any of our "Magnificent Retirement Mutual Funds," they are certainly earning their keep. If not, you may want to look elsewhere.

Do You Know the Top 9 Retirement Investing Mistakes?

Investing in underperforming mutual funds is just one of the key errors that can derail your retirement plans.

To learn more, read our just-released report: 9 Retirement Mistakes You Need to Avoid.